Tsg does not affect activation of Erk1/2. Primed alloreactive CD4⁺ T-cell lines were stimulated for the indicated time intervals by CD3 cross-linking after pretreatment either with media, TGF-β, or Tsg. Cell lysates were prepared and equal amounts (75 μg/sample) were analyzed by Western blot with mAbs specific for pErk1/2 and Erk1/2.