Delayed loss of microvilli in moesin-T558D–transfected cells in early stages of polarization. PBT cells were “nucleofected” with a moesin construct that mimics the unphosphorylated form (moesin-T558A-HA; A-B), or a construct that mimics the phosphorylated form (moesin-T558D-HA; C-D). Samples were prepared for conventional SEM using chemical drying with tetramethylsilane. After 30 seconds (A,C) and 60 seconds (B,D) cells were observed in early stages of polarization, identifiable by the presence of ruffles (arrowheads), but absence of a well-formed lamellipodium. Such cells in T558D-transfected cells generally retained coarse microvilli but in T558A-transfected cells had generally lost microvilli. All images were acquired at × 6000 and relative size was maintained during figure composition.