A CD4+T cells from wild-type (WT), CBLOST and CBLBOSTmice were left unstimulated (-) or stimulated for 2 min with anti-CD3 and anti-CD4 antibodies (+). Equal amounts of cell lysates were subjected to affinity purification on Strep-Tactin-Sepharose beads, followed by elution of proteins with D-biotin. Eluted proteins were analyzed by immunoblot with antibodies specific for CBLB and CBL. Equal amounts of proteins from whole cell lysates (WCL) were also probed for CBLB and CBL. Note that in the case of CBLB two bands are detected and likely corresponded to the presence of two isoforms differing at their N-terminus (http://www.uniprot.org/uniprot/Q3TTA7). Also shown are loading control corresponding to the same immunoblot probed with anti-CD5, and molecular masses (kDa). Data are representative of at least three experiments. 