Which of the Following Statements is NOT True of the PRb

Question

Which of the following statements is NOT true of the pRb protein?
A)pRb is functionally inactive when it is hyperphosphorylated.
B)pRb is mostly unphosphorylated during the G0phase of the cell cycle.
C)pRb is growth-promoting during early G1phase.
D)pRb phosphorylation is initiated by D-type cyclins and CDK4/6.
E)pRb is functionally inactivated at the R point.

Accepted Answer

pRb is growth-inhibitory during early GS phase, not growth-promoting. It functions to limit cell cycle progression until appropriate signals for cell division are present, which occurs at the R point. During this point, pRb is functionally inactivated through hyperphosphorylation.