Figure 7.

TGFβ-mediated apoptosis is dependent on prolonged p38 activation. (A) BL41 cells were cultured for 48 h in the presence of TGFβ (1 ng/ml) for various times. Lane 1, for the first hour of culture; lane 2, during the whole culture. For lanes 3 and 4, cells were activated with TGFβ for the first 16 h of culture, harvested, washed, and cultured for an additional 30 h in the absence (lane 3) or the presence of TGFβ (lane 4). (B) BL41 cells were activated for 48 h with TGFβ (1 ng/ml) in the absence (lane 1) or the presence of SB203580 (20 μM) during the whole culture (lane 2), from 16 to 48 h (lane 3), or for the last hour of culture (lane 4). Shrunken cells were counted by flow cytometry, as described in the legend to Figure 1.