Figure 3.

Expression of pRB-related p130 in the cytokine-dependent 6–1 cells. (A) Induction of p130 in asynchronously growing (Top) or growth-arrested (Middle) p130-transfectants, p130–1 and p130–5, was examined by immunoblotting with anti-p130. The cells were then restimulated with various doses of IL-2 for 24 h and IL-2-dependent cell proliferation was evaluated by measuring [³H]thymidine incorporation into DNA (Bottom). (B) The p130 transfectants were cultured in medium containing IL-2 or IL-3 in the presence of Tc or IPTG, and cell numbers were counted. (C) Induction of p130(Δ620–697) mutant that lacks the cyclin–CDK binding site or p130(Δ846–1119) mutant that lacks pocket region was examined by immunoblotting with anti-p130. (D) The stable transfectants for each mutant p130 were cultured in medium containing IL-3 in the presence of Tc or IPTG, and cell numbers were counted. The same result was reproduced twice for each clone.