For 24 or 48 hours, whole cell lysates isolated from GIST882 (B) or GIST-T1 (E) were analyzed for IGFBP3 expression by immunoblotting, or (C) conditioned medium from GIST882 cells analyzed for IGFBP3 levels by ELISA. rhIGFBP3, recombinant human IGFBP3.effects IGFBP3 itself has in the two GIST cell lines. Because GIST882 cells have detectable levels of endogenous cellular and secreted IGFBP3, we do