(A)His-p27WT was phosphorylated in vitro with activated Src. Mock treated (p27) or Src treated pY-p27 were incubated with cyclin E-Cdk2 and H1 kinase activity assayed. Equal input of mock vs. Src treated p27 shown.
(B)His-p27WT incubated without Src (no Src), with inactive Src (dead Src) and active Src are shown. pYp27 was precipitated with αpY-4G10.
Equal amounts of p27 from (B) were incubated with cyclin E-Cdk2. (C) p27, (D) Cdk2 and (E) Cyclin E were precipitated and associated proteins blotted.