CUL3 and neoplasm: When all the Onc2.3 tumors were analyzed together, we noted that the negative regulators of the Ras signaling pathway such as Rasa1 and Nf1 were commonly inactivated in liver and cuSCC, while genes encoding members of the E3 ubiquitin ligase such as Trip12 and Cul3 were frequently inactivated in all tumor types analyzed.