Figure 2.

Schematic representation of the Cdk phosphorylation sites in pRB. Position of the consensus Cdk phosphorylation sites in relation to the pRB protein is indicated. Phosphorylation of S230 has not been confirmed by either site directed methods or mass spectrometry in human pRB, but phosphorylation of the corresponding serine in mouse pRb (S224) has been observed by site directed methods (see text). Unless specified, amino acid numbering throughout the text will refer to human pRB. The A and B domains of the small pocket and large pocket and the carboxyl-terminus are indicated.