1 Supporting Informations Identification of MRC2 and CD209 receptors as targets for photodynamic therapy of retinoblastoma using mesoporous silica nanoparticles A. Gallud, a D. Warther, b M. Maynadier, c M. Sefta, d F. Poyer, e,# C. D. Thomas, e,# C. Rouxel, f O. Mongin, f M. Blanchard-Desce, f,# A. Morère, a L. Raehm, b P. Maillard, g,#* J.O. Durand, b,#* M. Garcia, a and M. Gary- Bobo. a* Mannose receptors were studied to better understand endocytosis mediated by glycosylated nanoparticles 1, 2 . Macrophage mannose receptor 1 (MRC1), C-type mannose receptor 2 (MRC2), lymphocyte antigen 75 (LY75) and phospholipase A2 receptor (PLA2R) have an overall structural homology but distinct ligand binding profiles 3, 4 . All of them are structurally organized into linear sequence of globular domains to compose a roughly 180 kDa receptor. A cysteine-rich domain is located at the extreme N-terminus, followed by a single fibronectin type-II domain and by eight to ten C-type lectin domains involved in carbohydrate recognition. They also possess a single transmembrane segment, a short cytosolic domain containing motifs able to recognize components of the endocytic pathway 3 . This one allows their recycling between the plasma membrane and the endosomes with a step of 10 rounds each hour in the case of MRC1. Only 10 to 30% of the receptors are recycled to cell surface and the majority resides inside the cell 5 . The potential targeting of CD209 receptor was also investigated. This mannose receptor contains a flexible neck region, a transmembrane region and a cytoplasmic tail that incorporates recycling and internalization motifs 6 . These properties make these lectins interesting for therapeutic targeting. Electronic Supplementary Material (ESI) for RSC Advances. This journal is © The Royal Society of Chemistry 2015