FIG. 10.

(A) Enforced expression of WTp110 but not DNp110 or an empty vector leads to the induction of cyclin D1 protein expression in serum-deprived NIH 3T3(M17) fibroblasts. Transfections were performed as described in the legend to Fig. 1, and the cells were serum deprived for 2 days. Arrowheads indicate the positions of nuclei in transfected cells. (B) The WTp110-dependent expression of cyclin D1 protein is sensitive to LY294002 (25 μM) and rapamycin (30 nM) but not DEX-induced expression of Ras(N17). (C) Percentages of cyclin D1-positive cells in the transfected population. The concentration of PD98059 was 30 μM. (D) Coexpression of either DNp110 or DNp85 but not DN-MAPK(ERK) suppresses WTp110 induction of cyclin D1 protein in quiescent cells. The cells were cotransfected with the indicated amounts (in micrograms) of expression plasmids together with 0.3 μg of pCAGGS-βgal and appropriate amounts of an empty vector so that the total amount of DNA per transfection was adjusted to 3.0 μg. The reduction in the amount of the expression plasmid for WTp110 from 1.3 to 0.7 μg by itself did not affect the percentage of cyclin D1-positive cells.