FIG. 4.

The inhibition of S-phase entry by microinjection of PLC-γ1 SH2-SH2-SH3 but not Grb2 SH2 or anti-Ras antibody is relieved by IP₃ and DAG. Quiescent MDCK cells were injected with the proteins indicated below, incubated at 37°C for 1 h, and then incubated with EGF (100 ng/ml) and BrdU with or without DAG for 15 h. Following fixation, the microinjected cells were identified by use of either FITC-conjugated avidin (A to D) or FITC-conjugated antirat antibody (E and F), and BrdU incorporation was detected by use of mouse anti-BrdU antibody followed by TRITC-conjugated antimouse antibody. (A) Cells injected with PLC-γ1 SH2-SH2-SH3; (B) cells injected with PLC-γ1 SH2-SH2-SH3 and IP₃ and treated with DAG1; (C) cells injected with Grb2 SH2; (D) cells injected with Grb2 SH2 and IP₃ and treated with DAG1; (E) cells injected with anti-Ras Y13-259; (F) cells injected with anti-Ras Y13-259 and IP₃ and treated with DAG1. Magnification, ×120.