Click on image to view larger version.

Fig. 2. Loss of expression of CDKIs does not result in escape from requirements for
MAPK activation. MEFs derived from p21Waf1/Cip1, p27Kip1
or p16Ink4-knockout mice were plated at a density of
2.5x104/ml. The following day the cells were placed in medium
containing 0.5% (v/v) FCS for 24-48 hours. The cells were then treated with
U0126 (20 µM final concentration) or vehicle control (DMSO) 60 minutes and
then stimulated with 10% (v/v) FCS for 16-20 hours followed by
immunofluorescence.