Forskolin delays tumor growth in vivo. Ten BALB/c Nude mice were subcutaneously injected with 5 × 105 MOP315.DsRed cells on day 0. On day 2 (panels A), groups of 5 mice received an intraperitoneal injection of forskolin (4-5 mg/kg) or vehicle. In a separate experiment (panel B), 5 mice received 3 subsequent injections with forskolin or vehicle on days 2, 4 and 6. In vivo imaging of DsRed fluorescence from the mice was measured daily with an IVIS Spectrum detection system. (A and B) Average total DsRed fluorescence from mice (n = 5) at the indicated time points relative to day 0. Arrows indicate the time of vehicle (open circles) or forskolin (closed circles) injections. Error bars represent SEM. *P < 0.05 relative to vehicle treated mice. (C) In vivo images of individual mice taken at day 7 from the one injection experiment (panel A).