ANUP monoclonal antibodies abrogate the effect of ANUP on KS cell growth inhibition. (A) KS Y-1 cells were seeded at a density of 1 × 10⁴/well on gelatin-coated 48-well plates. Cells were treated with various concentrations of ANUP alone or with ANUP antibodies at a concentration of 1 μg/mL. Cell proliferation was measured after 72 hours. The active preparation of hCG (A.P.L.; Wyeth Ayerst) inhibited KS cell proliferation (B and C), and this effect was not blocked by ANUP antibodies. KS cells were treated with hCG (A.P.L.) at various concentrations alone or in combination with ANUP antibodies (1 μg/mL each). Cell proliferation was measured at 72 hours. The data represent the mean ± SD of experiments performed in quadruplicate.