Antitumor effect of anti-HM1.24 MoAb on advanced RPMI 8226 tumors in SCID mice. Mice were injected subcutaneously with RPMI 8226 cells at day 0. The anti-HM1.24 MoAb treatment (100 μg/dose) was started 22 days after tumor inoculation for 50 days either once (•, n = 5) or twice (▪, n = 9) a week. Control IgG was used for negative controls (○, n = 9). Data represent the mean ± standard error of mean (SEM). *P < .05, †P < .005, ‡P < .0001, compared with the control IgG-treated group.