Perifosine inhibits human MM cell growth in vivo. (A-B) Immunodeficient BNX mice were inoculated subcutaneously in the flank with 3 × 10⁷ MM.1S cells in 100 μL RPMI 1640 medium and 100 μL Matrigel. Oral perifosine was administered daily (red line; 36 mg/kg, n = 7) and weekly (green line; 250 mg/kg, n = 7) starting after the development of measurable tumor. Perifosine significantly inhibited MM tumor growth (A) (P = .04) and increased survival (B) (P = .001) compared with the control group treated with vehicle (blue line; normal saline, n = 6) only. Error bars in panel A represent ± 1 SD of 7 mice in the treated groups and 6 mice in the control group. (C) Significant growth inhibition of subcutaneous tumor was observed after 4 weekly treatments with perifosine (250 mg/kg). (D) Tumor tissues from mice treated with control vehicle or with weekly perifosine were harvested; whole-tissue lysates were subjected to Western blotting using anti–p-Akt and Akt Abs.