Fig. 4. Effects of IFN-{alpha} on IL-2-mediated up-regulation and phosphorylation of the pocket proteins. Immunoblot analysis of pRb, p130, and p107 expression in quiescent (Day 0), PHA-treated (Day 3), IL-2-treated (Days 4–6), and IL-2/IFN-{alpha}-treated (Days 4–6) cells. Tubulin served as control for equal loading in each lane. The monoclonal p130 antibody used also detected an nonspecific band (*); this band has been described previously (27) .