PILSAP is required for CDK activity and Rb phosphorylation upon VEGF stimulation. After treatment with ODNs or with LT, MSS31 cells were serum starved for 24 hours and then stimulated with VEGF (50 ng/mL) for 12 hours. (A) CDK 4 and (B) CDK 6 activities were analyzed by immune-complex kinase assays. The densitometric intensities were determined and normalized with those of the total protein level. (C) Phosphorylation state of the Rb protein was analyzed by immunoblotting.