Tyrosine-phosphorylated PAG recruits Csk in cured cells.

(A) Crude membrane extracts or membrane extracts after passing through anti-PAG immunosorbent from untreated or BW720c-treated TpM409 cells were prepared and probed by Western blotting with antibodies directed against PAG/Cbp (top) and against phosphotyrosine (bottom). (B) PAG was immunoprecipitated from membrane extracts of untreated or BW720c-treated TpM409 cells, and PAG abundance (top), tyrosine phosphorylation (middle), and Csk association (bottom) were determined by Western blotting. (C) Increased PAG expression in resting B cells is reverted by growth stimulation: PAG was immunoprecipitated from bovine B cells or bovine B cells stimulated with PMA/ionomycin for 4 hours and probed by Western blotting with anti-PAG antibodies.