Fig. 6. Increased GM1 expression levels following addition of GM1 to the cell medium. (A) Dot blot analysis of GM1 expression in 0.25, 0.5, 1, 2 and 4 µg lysates from CaCo-2 and HeLa cells grown in the absence (GM1–) or presence (GM1+) of 5 mM GM1 in the medium for 4 hours followed by a 4-hour chase in regular medium. (B) The number of cells expressing high levels of GM1, as determined by CTX labeling, was counted in HeLa cells grown in regular medium (GM–) and GM1 supplemented medium (GM+).