Prostate cancer cell lines compared for their cell spreading responses to treatment with stromal cell-conditioned media (SCM). (A) All cell lines, except LNCaP, increased cell spreading on laminin, following exposure to the SCM. (B) C4-2 cell attachment to laminin, following treatment with SCM or purified HGF. Cells were allowed to attach for 90 min., at which point ~25% of untreated C4-2 cells showed membrane protrusions. Induction of cell spreading, as seen for both SCM and purified HGF, is reversible by addition of anti-HGF antibody. Conditioned media from three primary stromal cell lines gave similar results (data not shown). Experimental cell spreading is shown as a percentage of control, untreated cells. Statistically significant differences from the control in each group were below P =< 0.05 (*). For each data point n = 6 or more.