(E) Quantification of the ratio of PM signals to the cytosolic signals of wild-type EGFP-GRAM1b (WT) and mutant EGFP-GRAM1b (G187L), as assessed by confocal microscopy and line scan analysis from GRAMD1 TKO HeLa cells, expressing indicated constructs, with or without SMase treatment (100 mU/ml for 1 hour at 37°C), as shown in (D) (mean ± SEM, n = 10 cells for each condition; data are pooled from one experiment). 