Fig. 2. FasL interacts with members of the Src family of tyrosine kinases. (A) GST alone or GST-fusion proteins of the SH3 domains of Lyn, Lck, Fyn or Fgr were used to pull-down FasL from cells lysates of RBL expressing FasL-GFP. The western blot was probed with anti-FasL, G247-4. Molecular mass markers are shown (kDa) and the arrow indicates the position of FasL-GFP. The 40 kDa band is a degradation product. (B) Agarose gel separation of RT-PCR products made with primers specific for rat Fgr, Fyn, Lyn and Lck mRNA isolated from RBL, YT and a mixed lymphocyte reaction (MLR) containing activated CD4+ and CD8+ T lymphocytes. Products were verified by sequencing. DNA ladder markers are shown on the left.