Altered pattern of tyrosine phosphorylation and defective Ras activation in IL-10

 + TGF-β–tolerant T cells. (A) Primed and tolerant T cells from B6 mice were stimulated in vitro as described in “Materials and methods” for the indicated time intervals. Cell lysates were prepared and were analyzed by SDS-PAGE, transferred to nitrocellulose membrane, and blotted with antiphosphotyrosine mAb. Blots were stripped and reblotted with the indicated peptide-specific antiserum to determine the identity of the differentially phosphorylated substrates. (B) As an indicator of Ras activation, the serine phosphorylation of ERK1 and ERK2 MAPK was examined by blotting with phospho-ERK–specific antibody that recognizes only the activated phosphorylated form of ERK1 and ERK2 (top panel). The blot was stripped and reprobed with ERK-specific antibody, which recognizes total ERK (bottom panel).