Increased T758 phosphorylation in the β2-chain upon Cbl-b deficiency mediates LFA-1 activation. (A) Disruption of the association of 14-3-3β with the β-chain of LFA-1 abrogates the enhanced ICAM-1 adhesion of Cbl-b^−/− BMDMs. WT (□) and Cbl-b^−/− (■) BMDMs were transfected with R18wt or R18mut DNAs, and allowed to adhere onto immobilized ICAM-1. Cell adhesion is represented as percentage of control. The adhesion of R18mut-transfected WT BMDMs represents the 100% control. Data are means plus or minus SD (n = 3). (B) Increased T758 phosphorylation in the β2-chain of LFA-1 due to Cbl-b deficiency. T758 phosphorylation of β2-integrin (CD18) was determined in PMA-treated WT and Cbl-b^−/− monocytes. Immunoprecipitation of CD18 was performed followed by Western blot using a phosphospecific T758 CD18 antibody or an antibody against total CD18. (C) Adhesion of WT or Cbl-b^−/− BMDMs to immobilized ICAM-1 is shown in the absence (□) or in the presence (■) of the PKC inhibitor Gö6983 (50 nM). Cell adhesion is represented as the percentage of adherent cells. Data are means plus or minus SD. Similar results were observed in 3 separate experiments. ^#P < .01; ns, nonsignificant.