Rabbit anti-cdk2 was used at a 1:200 dilution to detect cdk-2 in asynchronous HeLa cell lysates (run in duplicate). Approximately 50 ?g of lysate was separated on a 15% SDS-PAGE gel. Cdk-2 is indicated by an arrowhead as a 32-33 kDa band. Note that multiple isoforms as well as phosphorylated forms of cdk-2 may be detected by this antibody. Primary antibody was reacted at RT for 1 h. After subsequent washing, a 1:5,000 dilution of HRP conjugated Gt-a-Rabbit IgG preceded color development.