FIG. 2.

PC3-processed PDGF D is biologically active. Serum-starved NIH 3T3 cells were stimulated for 10 min with CM collected from PC3-PDGF D, PC3-neo, LNCaP-PDGF D, and LNCaP-neo. Serum-starved NIH 3T3 cells stimulated with serum-free (SF) medium or SF medium supplemented with 25 ng/ml PDGF BB served as negative and positive controls, respectively. Fifty micrograms of NIH 3T3 lysate was resolved by reducing SDS-PAGE and immunoblot analyzed using an antibody specific to active extracellular signal-regulated protein kinase (pERK1/2). To determine basal levels of ERK1/2, the same blot was stripped and immunoblotted with an antibody that recognizes both active and inactive forms of ERK1/2.