Using DNA tumor virus oncoproteins as tools to disrupt cellular proteins' functions, we've learned that functional retinoblastoma protein is essential for the lens cells to exit the cell cycle and differentiate and that one of the likely roles for Rb in this process is to repress the activity of the E2F1 transcription factor. The ultimate fate of these lens cells in which Rb is inhibited is apoptosis. The p53-independent pathway may also function in normal lens cell differentiation, which we view as a modified form of apoptosis. The FGF signaling pathways appears to be an important controller of lens cell differentiation and survival. Members of the ICE family of proteases and bcl2 family of apoptosis regulators are expressed in the lens and protease activity associated with multiple ICE family members can be detected at specific times in lens development, leading to the suggestion that these families are important in normal lens development.
Cellular genes modify risk to retinoblastoma in transgenic mice.
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