L1CAM and retinoblastoma: As ectodomain shedding of L1CAM is mediated by ADAM10 and ADAM17 and the soluble ectodomain of L1CAM is believed to mediate cell migration, protection from apoptosis, and stimulation of cell survival [2, 19, 20, 21, 22], we investigated the expression of these sheddases in seven RB cell lines by real‐time PCR (Fig. S2A,B) and western blot analysis (Fig. 8A).