Fig. 1.

RhoA mutants differentially regulate VEGF-driven angiogenesis in mouse skin. Retroviral packaging cells together with VEGF-transfectants (VEGF/SK-MEL2) were combined with basement membrane Matrigel and injected s.c. On day 6, animals were harvested and skin overlying the Matrigel implants was dissected. Control, negative control, i.e., Matrigel without cells; +VEGF, positive control consisting of VEGF transfectants plus packaging cells expressing retrovirus without Rho insert; VEGF + N19RhoA, VEGF transfectants plus packaging cells expressing retrovirus encoding dominant negative RhoA; VEGF + V14RhoA, VEGF transfectants plus packaging cells expressing retrovirus encoding an active RhoA mutant. Neither packaging cells nor untransfected SK-MEL2 cells provoked angiogenesis detectably (data not shown); therefore, angiogenesis depicted here is VEGF-dependent. V14RhoA cooperated with VEGF to promote the appearance of new blood vessels (characterized by tortuous, “corkscrew” appearance and marked with arrows) but N19RhoA was inhibitory. Moreover, abundant newly formed small blood vessels in the V14RhoA group were rapidly perfused (<10 min) after tail-vein injection of Evans blue dye tracer (Far Right). Photographs are representative examples of results consistently obtained in three separate experiments each with at least eight specimens per group. (Scale bar = 1 mm.)