PHA-739358 effectively inhibits growth of K562 in vivo. K562 cells were injected subcutaneously in SCID mice. When tumors reached an estimated weight of 100 to 150 mg, the vehicle (■), PHA-739358 (♦), or IM (▾) was administered for 10 days. PHA-739358 and IM were well tolerated and significantly suppressed tumor growth compared with controls. Error bars represent SD.