Anti-PTN antibody inhibits MM proliferation in the SCID-hu myeloma model, LAGλ-1. The human myeloma tumor LAGλ-1 was implanted intramuscularly into SCID mice and hIgG production was measured by ELISA. When hIgG was detected, anti-PTN antibody (3 or 10 mg/kg) or control IgG (cIgG, 10 mg/kg) was administered intraperitoneally twice weekly. (A) Anti-PTN treatment markedly reduced hIgG production and the volume of the myeloma tumor (B) in vivo. *P < .005, **P < .05.