T544 phosphorylation cycling is required for stable ERM-1 localization in the intestine. Stills from time-lapse movies (A,C,E) and FRAP curves (B,D,F) of GFP-tagged ERM-1 variants at the apical membrane of the intestine of L1 larvae (n=7 for ERM-1::GFP, n=8 for ERM-1[T544A] and n=7 for ERM-1[T544D]), the apical membrane of the excretory canal of L4 larvae (n=5 for ERM-1::GFP, n=4 for ERM-1[T544A] and n=4 for ERM-1[T544D]), or the basolateral membrane of the germline of L4 larvae (n=10 for ERM-1::GFP, n=7 for ERM-1[T544A] and n=7 for ERM-1[T544D]). Thin lines and shading represent the mean±s.d., and thick lines represent curve fitting of averaged FRAP data with a double exponential equation.