Interestingly, we found that in Rb1 cKO retinae, a mouse model that does not develop retinoblastoma due to compensation by p107, HELLS mRNA and protein expression follows a similar dynamic as wild-type retinae, with maximal expression during embryonic stages (E17.5-P0), repression after postnatal day 2 (P2) and significant reduction in protein levels after postnatal day 6 (P6; Fig. 3d). This evidence concerns the gene RB1 and retinoblastoma.