A, B CD4+T cells from wild-type, Cblb-/- and Cd5-/- mice were stimulated for 1 min with anti-CD3 and anti-CD4 antibodies (+). CBL (A) were immunoprecipitated from equal amounts of protein lysates. Level of ubiquitylation and amount of CD5 associated proteins were evaluated by immunoblot with antibodies specific for the proteins specified in the left margin. Whole cell lystates (WCLs) were also analyzed with the specified antibodies. Molecular masses are shown (kDa). Data are representative of at least 2 experiments. 