GPC1 and neoplasm: Results of the second in vivo study, in which i.p. administration of anti-GPC1 mAb at a modified dosing regimen was started two weeks after tumor cell inoculation, demonstrated that anti-GPC1 mAb treatment at 1 mg/kg, 10 mg/kg and 50 mg/kg significantly reduced the phospho-Src (Tyr416) levels in A549 tumors by 35% (P < 0.05), 75% (P < 0.01) and 68% (P < 0.01), respectively (Figure 14B).