Journal of Biophysical Chemistry, 2014, 5, 67-77 Published Online May 2014 in SciRes. http://www.scirp.org/journal/jbpc http://dx.doi.org/10.4236/jbpc.2014.52008 How to cite this paper: Fardilha, M., et al. (2014) Phosphoprotein Phosphatase 1 Isoforms Alpha and Gamma Respond Dif- ferently to Prodigiosin Treatment and Present Alternative Kinase Targets in Melanoma Cells. Journal of Biophysical Che- mistry, 5, 67-77. http://dx.doi.org/10.4236/jbpc.2014.52008 Phosphoprotein Phosphatase 1 Isoforms Alpha and Gamma Respond Differently to Prodigiosin Treatment and Present Alternative Kinase Targets in Melanoma Cells Margarida Fardilha 1* , João Figueiredo 1 , Margarita Espona-Fiedler 2 , Juliana Felgueiras 1 , Luís Korrodi-Gregório 1 , Sara L. C. Esteves 1 , Sandra Rebelo 3 , Odete A. B. da Cruz Silva 3 , Edgar da Cruz e Silva 1 , Ricardo Pérez-Tómas 2 1 Laboratory of Signal Transduction, Centre for Cell Biology, Biology Department and Health Sciences Department, University of Aveiro, Aveiro, Portugal 2 Department of Pathology and Experimental Therapeutics, Cancer Cell Biology Research Group, University of Barcelona, Barcelona, Spain 3 Laboratory of Neuroscience, Centre for Cell Biology, Biology Department and Health Sciences Department, University of Aveiro, Aveiro, Portugal Email: * mfardilha@ua.pt Received 17 March 2014; revised 17 April 2014; accepted 24 April 2014 Copyright © 2014 by authors and Scientific Research Publishing Inc. This work is licensed under the Creative Commons Attribution International License (CC BY). http://creativecommons.org/licenses/by/4.0/ Abstract Reversible protein phosphorylation is a central regulatory mechanism of cell function. Deregula- tion of the balanced actions of protein kinases and phosphatases has been frequently associated with several pathological conditions, including cancer. Many studies have already addressed the role of protein kinases misregulation in cancer. However, much less is known about protein phos- phatases influence. Phosphoprotein Phosphatase 1 (PPP1) is one of the major serine/threonine protein phosphatases who has three catalytic isoforms: PPP1CA, PPP1CB, and PPP1CC. Its function is achieved by binding to regulatory subunits, known as PPP1-interacting proteins (PIPs), which may prefer a catalytic isoform. Also, some inhibitors/enhancers may exhibit isoform specificity. Here we show that, prodigiosin (PG), a molecule with anticancer properties, promotes the forma- tion of PPP1CA-AKT complex and not of PPP1CC-MAPK complex. Both, AKT and MAPK, are well- known PIPs from two pathways that crosstalk and regulate melanoma cells survival. In addition, the analysis performed using surface plasmon resonance (SPR) technology indicates that PPP1 * Corresponding author.