Fig. 4. Serum stimulation of serum-starved AKR-2B cells results in a decrease in p202 levels. Subconfluent cultures of murine AKR-2B cells were incubated in growth medium supplemented with either 10% (Lane 2) or 1% (Lanes 3–7) FBS for 3 days. Cultures in Lanes 4–7 were washed with warm PBS, and cells were serum stimulated with growth medium supplemented with 10% serum for 4 (Lane 4), 8 (Lane 5), 14 (Lane 6), or 24 h (Lane 7). As a control, cells were treated with IFN for 48 h (Lane 1). The total cell extracts were prepared as described in "Materials and Methods." Extracts containing 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 band.