TGF-β₁ inhibits Jo2-induced apoptosis of Lin⁻ BM cells. Eighty thousand Lin⁻ BM cells were cultured for 52 hours in 96-well microtiter plates in complete IMDM supplemented with cytokines as indicated. For the last 22 hours cultures were continued in the absence () or presence (▪) of 1 μg/mL Jo2. Cultures were analyzed for apoptotic cells as described in Materials and Methods. Freshly isolated Lin⁻ BM cells contained less than 1% apoptotic cells (data not shown). An irrelevant hamster IgG control antibody (1 μg/mL) did not affect apoptosis or cell numbers (data not shown). Results represent the mean values of three independent experiments. Error bars show the SEM.