Fig. 1. Inactivation of ERM proteins in L cells by microinjection of C3 transferase. (A-C) Rh-dextran and C3 transferase were co-microinjected into L cells. After a 30 minute incubation, cells were fixed with TCA/formaldehyde, and microinjected cells were identified by the fluorescence of Rh-dextran (A). Cells were then doubly stained with anti-ERM mAb, CR22 (B) and anti-CPERM mAb (C). C3 induced dephosphorylation of CPERMs (C), with concomitant translocation of ERM proteins from microvilli to the cytoplasm (B). (D-G) L cells grown on CELLocate^TM coverslips were microinjected with C3/F-dextran followed by glutaraldehyde fixation. Their phase-contrast (D) and fluorescence (E) images were recorded to identify microinjected cells. Scanning electron microscopy showed that a non-microinjected cell (arrowheads) bore numerous microvilli on its surface (F), whereas a microinjected cell (arrow) was characterized by a smooth cell surface (G). Bars, A-C, 10 µm; D, E, 10 µm; F, G, 2 µm.