Expression of Rb protein and p21 in Karpas 299 cells after CD30 activation.

After synchronization, cells were fed serum and allowed to grow. Forty hours after addition of serum, in the absence of HeFi-1 all the Rb protein expressed is in phosphorylated form (upper band), whereas the HeFi-1 treated cells demonstrate a significant amount of unphosphorylated Rb protein. p21 is not expressed in the control cells, whereas the CD30-activated cells have high p21 expression at 40 hours after CD30 activation.