modulate Bcl2 phosphorylation and suggest that PKC a-medi- ated Bcl2 phosphorylation may be relevant to chemoresistance in AML. S Kurinna 1 , M Konopleva 2 , SL Palla 3 , W Chen 2 , S Kornblau 2 , R Contractor 2 , X Deng 4 , WS May 4 , M Andreeff 2 and PP Ruvolo 1,2 1 Division of Cell Signaling, Institute of Molecular Medicine, University of Texas Health Science Center, Houston, TX, USA; 2 Department of Blood and Marrow Transplantation, MD Anderson Cancer Center, Houston, TX, USA; 3 Department of Biostatistics and Applied Mathematics, MD Anderson Cancer Center, Houston, TX, USA and 4 Shands Cancer Center, University of Florida, Gainesville, FL, USA E-mail: Peter.P.Ruvolo@uth.tmc.edu References 1 Yang E, Korsmeyer SJ. Molecular thanatopsis: a discourse on the Bcl2 family and cell death. Blood 1996; 88: 386–401. 2 Deng X, Kornblau SM, Ruvolo PP, May WS. Regulation of Bcl2 phosphorylation and potential significance for leukemic cell chemoresistance. J Natl Cancer Inst 2000; Monograph 28: 30–37. 3 Haldar S, Jena N, Croce CM. Inactivation of Bcl2 by phosphoryla- tion. Proc Natl Acad Sci USA 1995; 92: 4507–4511. 4 Ito T, Deng X, Carr BK, May WS. Bcl2 phosphorylation required for anti-apoptosis function. J Biol Chem 1997; 272: 11671–11673. 5 Ruvolo PP, Deng X, Carr BK, May WS. A functional role for mitochondrial PKC a in Bcl2 phosphorylation and suppression of apoptosis. J Biol Chem 1998; 273: 25436–25442. 6 Deng X, Ruvolo P, Carr B, May WS. Survival function of ERK1/2 as IL-3-activated staurosporine-resistant Bcl2 kinases. Proc Natl Acad Sci USA 2000; 97: 1578–1583. 7 Konopleva M, Tsao T, Ruvolo P, Stiouf I, Estrov Z, Leysath CE et al. Novel triterpenoid CDDO-Me is a potent inducer of apoptosis and differentiation in acute myelogenous leukemia. Blood 2002; 99: 326–335. 8 Kornblau SM, Vu HT, Ruvolo P, Estrov Z, O’Brien S, Cortes J et al. Bax and PKCa modulate the prognostic impact of Bcl2 expression in acute myelogenous leukemia. Clinical Cancer Res 2000; 6: 1401–1409. 9 Pagano M, Halvorsen K. An algorithm for finding the exact significance levels of r x c contingency tables. J Am Stat Assoc 1981; 76: 731–934. The JAK2 V617F mutation identifies a subgroup of MDS patients with isolated deletion 5q and a proliferative bone marrow Leukemia (2006) 20, 1319–1321. doi:10.1038/sj.leu.2404215; published online 13 April 2006 The detection of JAK2 V617F somatic mutation has greatly enhanced our understanding of the pathogenesis of the bcr/abl- negative chronic myeloproliferative disorders (MPD). An in- creased sensitivity to erythropoietin and growth factor indepen- dence is reported in the presence of the mutation. 1–3 Four independent groups recently report JAK2 V617F mutation in the majority of patients with polycythaemia vera and up to 50% of essential thrombocythaemia and idiopathic myelofibrosis. 1–4 An increased incidence of thrombosis, haemorrhage and fibrotic transformation in the presence of the mutant allele is reported. 3 Larger studies are however required to elicit the true prognostic significance of the mutation. The finding of JAK2 V617F mutation outside of the classical MPDs is uncommon with reports of low incidence in chronic myelomonocytic leukaemia, atypical chronic myeloid leukae- mia, hypereosinophilic syndrome and chronic neutrophilic leukaemia. 5 The myelodysplastic syndromes (MDS) are a hetero- geneous group of clonal haematopoietic stem cell disorders characterised by peripheral blood cytopenias, ineffective erythropoiesis and increased apoptosis. The 5q syndrome is a subgroup of MDS characterised by an interstitial deletion of the long arm of chromosome 5(q31–q33) with macrocytic anaemia, normal or elevated platelet count, hypolobated megakaryocytes and associated with a favourable prognosis. However, cases presenting with 5q deletion and marked elevation of the platelet count in association with a hypercellular bone marrow display characteristics more suggestive of an overlap syndrome (MDS/ MPD). We analysed 97 patients from six European centres known to have a diagnosis of MDS and deletion, 5q abnormality for the presence of JAK2 V617F mutation. Isolated deletion of 5q was detected in 81/97 cases, whereas additional cytogenetic abnormalities were noted in 16/97. The diagnosis of MDS was based on the World Health Organization Classification. A summary of patient characteristics is outlined in Table 1. Ethical approval was obtained before study commencement. Samples for analysis were obtained from archived bone marrow aspirate slides, archived cytogenetic samples or peripheral blood. The mutant JAK2 allele was detected using an allele-specific- polymerase chain reaction (AS-PCR). 4,6,7 The presence of the mutation and ratio of mutant to wild-type JAK2 allele was confirmed in 2/6 mutant cases using pyrosequencing. Polymer- ase chain reaction products were generated using AS-PCR primer sequences. Sequences were read from a reverse sequencing primer 5 0 -TCTCGTCTCCACAGA-3 0 . Pyrosequen- cing reactions were run on a Biotage PSQ HS 96 pyrosequencer. In a patient with JAK2 mutation, cells from bone aspirate were subjected to progenitor cell culture (CFU-GM- and BFU-E- derived colonies) or subfractionated into CD34 þ ve cells, followed by molecular analysis. Peripheral blood from the same case was also subfractionated into CD14, CD15, CD3 and CD19 þ cells using antigen-specific microbeads followed by selection using the AutoMacs cell separator Milteny. In the case of progenitor cultures, PCR was performed directly on the cells without prior DNA purification. DNA was extracted from subfractionated cells using Charge Switch reagents (Invitrogen, Inchinnan Business Park, Fountain Drive, Paisley, UK). All DNA extraction and cell separation kits were used according to the manufacturer’s instructions. Samples were processed in accordance with standard cytogenetic methods. CD34 þ cells were probed for 5q using the Vysis LSI EGR1 (5q31), spectrum orange D5S23 and spectrum green D5S721 probe, according to the manufacturer’s instructions (Abbot Laboratories). 100K Affymetrix SNP analysis of DNA extracted from CD34-positive cells was performed using Letters to the Editor 1319 Leukemia