Fig. 3. Dephosphorylation leads to inactivation of ERM proteins in L cells. (A) Control L cells (a,b) and 10 nM staurosporine-treated L cells (c,d) were doubly stained with anti-ERM mAb, CR22 (a,c), and anti-CPERM mAb (b,d). Staurosporine induced a dephosphorylation of CPERMs and translocation of ERM proteins from microvilli to the cytoplasm. Scanning electron microscopy showed that a staurosporine-treated L cell lost microvilli on its cell surface (e). Bars, a-d, 10 µm; e, 2 µm. (B) L cells cultured in the absence (control) or presence (stauro.) of 10 nM staurosporine were homogenized and centrifuged. Equivalent amounts of supernatant (S) and pellet (P) were subjected to immunoblotting with anti-ERM pAb, TK89. Note that staurosporine induced translocation of ERM proteins from the insoluble to soluble cell fraction (S).