Effects of R115777 on the growth of fresh myeloma cells from patients. The cells were cultured in quadruplicate at a density of 2.5 × 10⁵ cells/mL in 96-well flat-bottomed tissue-culture plates with concentrations of 0 (control) and 1.0 × 10^-7 M (A) or 1.0 × 10-8 M (B) of R115777 for 72 hours at 37°C in a humidified atmosphere of 5% CO₂ in air. R115777 inhibited the growth of fresh myeloma cells in all patients examined at 1.0 × 10^-7 M and 7 of 10 patients at 1.0 × 10^-8 M, but the degree of inhibition differed among the patients. Values represent means ± SDs of quadruplicate cultures. ^*P < .01.