Syngenic tumor implantation model was performed as described in the Materials and Methods. (a) siPigpen did not inhibit Lewis lung carcinoma (LLC) cell proliferation in vitro. Data indicate means and SDs, n = 10. (b) siPigpen inhibited tumor growth of LLC. Data indicate means and SEMs, n = 10 and 11 for scr‐ and siPigpen, respectively (days 5, 8, 10) and n = 8 (day 14). (c) siPigpen inhibited tumor angiogenesis. Data indicate means and SDs, n = 15 (scrPigpen) or 10 (siPigpen). *P < 0.05, **P < 0.01. (d) Representative immunohistochemistry (IHC) of CD31 (red), pigpen (green), and nuclei (blue) is shown. Bar = 50 μm.