Fig. 3. Addition of serum growth factors to the culture medium, under reduced serum conditions, abrogates the increase in p202 levels. A, subconfluent cultures of murine AKR-2B cells were incubated in growth medium supplemented with either 10% (Lane 2) or 1% (Lanes 3–5) FBS along with 10 (Lane 4) or 100 ng/ml human recombinant PDGF-AB (Lane 5) for 3 days. As a control, AKR-2B cells were treated with IFN for 48 h (Lane 1). Cells extracts were prepared as described in Fig. 1 A, and equal amounts of proteins were analyzed by immunoblotting using the anti-p202 antibody (top panel). The same membrane was subsequently probed with antibodies to ß-actin (bottom panel) to control loading of equal amounts of proteins in the lanes. An arrow indicates the p202 protein band. B, subconfluent cultures of murine AKR-2B cells were incubated in growth medium supplemented with either 10% (Lane 1) or 1% (Lanes 2–4) FBS along with 10 (Lane 3) or 20 ng/ml recombinant bFGF (Lane 4) for 3 days. Cells extracts were prepared as described in Fig. 1 A, and equal amounts of proteins were analyzed by immunoblotting using the anti-p202 antibody (top panel). The same membrane was subsequently probed with antibodies to ß-actin (bottom panel) to control loading of equal amounts of proteins in the lanes. An arrow indicates the p202 protein band. C, subconfluent cultures of murine AKR-2B cells were incubated in growth medium supplemented with either 10% (Lane 2) or 1% (Lanes 3–5) FBS along with 4 (Lane 4) or 8 ng/ml recombinant TGF-ß 1 (Lane 5) for 3 days. As a control, AKR-2B cells were treated with IFN for 48 h (Lane 1). Cells extracts were prepared as described in Fig. 1 A, and equal amounts of proteins were analyzed by immunoblotting using the anti-p202 antibody. An arrow indicates the p202 protein band.