DHFR and retinoblastoma: A series of canonical pathways, including those involved in Rb (Retinoblastoma)/E2F cell cycle (Rb, E2f2, E2f3, E2f5, Cdk6, DHFR), Notch (Dll1, Notch 2, Jag1), Wnt (Wnt, Axin2, Wisp2/Ccn5) and NF-κB (Ikbip) were found to participate in this network.