DLX4 stimulates tumor angiogenesis and ascites formation in i.p. xenograft models of ovarian cancer by inducing iNOS. Female nude mice (n = 5 per group) were inoculated i.p. with equivalent numbers of cells (1 x 106) of vector-control, +DLX4 and +DLX4 + shNOS2 ES2 lines and sacrificed at 20 days thereafter. (A) Volume of ascites. (B) Average numbers of microvessels were calculated in omental tumors by scoring five random 100x microscopic fields of CD34-stained tissue sections of each mouse. (C) Representative examples of CD34 staining in omental tumors. Bar, 100 μm.