Effect of tamoxifen on proliferation of MM cell lines and MM patient cells. ARH 77, OCI My-5, RPMI 8226, S6B45, and U266 MM cell lines (A) as well as purified MM cells from 2 patients (B) were cultured with 0.5 (▪), 5.0 (▨), and 50 (▧) μmol/L of TAM for 48 hours. ³H-TdR uptake was compared with DNA synthesis of cells cultured in media alone. *P < .05. Mean CPM and SEM for media alone cultures were as follows: ARH (11,528 ± 3,423), OCI-My-5 (11,315 ± 593), RPMI 8226 (329,161 ± 6,448), S6B45 (90,722 ± 3,887), U266 (29,748 ± 3,778), MM patient no. 1 (3,277 ± 1,246), and MM patient no. 2 (16,316 ± 2,329).