VSX2 and retinoblastoma: The Y79 cell line is a human retinoblastoma cell expressing a heterogeneous populations for both immature and mature retinal cell type-specific markers, such as Cone Rod Homeobox (CRX), Visual System Homeobox 2 (VSX2), Protein Kinase C-alpha (PKC-α), Retinoid X Receptor gamma (RXRγ), thyroid hormone receptor beta-2 (TRβ-2), Neural Retina-Specific Leucine zipper (NRL) and recoverin (Sakata and Yanagi, 2008; Xu et al., 2009; Oshikawa et al., 2011; Cassidy et al., 2012; Han and Townes-Anderson, 2012).