Influence of hematopoietic stimulatory cytokines (A) or TGF-β1 (B) on proliferation of primary mammary carcinoma cells. Primary mammary carcinoma cells were precultured in -MEM/10% FCS for the indicated periods. Enriched tumor cells (purity >95% of CK-positive and Ber-Ep4–positive cells) were cultured for 7 days in -MEM/10% FCS alone or with 10 ng/mL SCF, 3 ng/mL IL-1β, 100 ng/mL IL-3, 100 ng/mL IL-6, and 1 U/mL EPO (S136E) and/or 30 ng/mL of TGF-β1. (▪) Controls; (□) S136E; (▨) TGF-β1; (▩) TGF-β1 + S136E. Results represent the mean values ± SD of duplicate determinations. A P value greater than .05 was obtained when comparing the mean values of both groups in a two-tailed Student’st-test in (A). Statistical significant differences (P < .05) were recorded when comparing the control group (no cytokines) with either the TGF-β1 or the S136E plus TGF-β1 group in (B) using a two-tailed Student’s t-test.