Figure 1.

In vivo RB phosphorylation at S780, S795 and S807/S811 following transient co-transfections with cyclins D and E. Panel A) H2009 RB(-) cells were transiently transfected with parental RB vector alone (vector), wildtype RB (wt), or indicated lp mutants along with parental cyclin vector alone (-) or indicated cyclin plasmids. At 72 hours, lysates were subjected to sequential immunoprecipitation with a pan-RB antibody (G3-245) followed by immunoblotting using G3-245 for total RB protein levels or the indicated RB phospho-specific antibodies. Panel B) Yeast two-hybrid assay of mutant and wt RB cDNA to SV40 large T antigen using previously reported beta-galactosidase binding assay. ³