Fig. 4

P19 H-Ras does not activate cell growth. DKO H-Ras^(−/−)/N-Ras^(−/−) fibroblasts that stably express pEGFP (negative control), pEGFP-p19 and pEGFP-p21 were studied by direct cell-proliferation assay. Cells were harvested and plated in 96 wells (10,000 cells/well) on six microplates in sextuplicate and incubated at 37 °C, 5 % CO₂ with DMEM/10 % FCS. After the desired time, the microplates were washed and frozen. Cells were quantified with the green fluorescent dye CyQuant (Invitrogen) according to the manufacturer’s instructions. Fluorescence measurements were performed using a microplate reader with excitation at 485 nm and detection at 530 nnm