Selective inhibition of PDGFRβ inhibits growth of LLC and B16/PDGF-BB tumors with paracrine PDGF-BB signaling. (A, B) Dose-response analysis of treatment with 1-NaPP1 (15, 30 and 45 mg/kg/day) (A) or imatinib (75, 150 and 250 mg/kg/day) (B) of mice with Lewis lung carcinoma cells grown subcutaneously. (C, D) Effect of 1-NaPP1 (30 mg/kg/day) and imatinib (150 mg/kg/day) on growth of LLC (C) and B16/PDGF-BB tumors (D) in ASKA mice for 10 days (n= as stated in the figure). *** p<0.001. (E) LLC tumor lysates from mice treated with vehicle, 1-NaPP1 (30 mg/kg) or imatinib (150 mg/kg) were prepared and incubated overnight with WGA-beads. Retained proteins were analyzed by immunoblotting (IB) using a pY857 PDGFRβ antibody. Representative immunoblots out of two independent experiments are shown.