Fig. 2.

Vit C treatment alters expression and activity of ceramide metabolic enzymes. Human primary keratinocytes (KC) were cultured in high Ca²⁺-supplemented medium with or without Vit C, as described in materials and methods. Protein expressions of serine palmitoyltransferase (SPT) (A) and ceramide synthase (CerS) (C) were measured by western immunoblot analysis. Enzyme activities of SPT (B), CerS (D), and sphingomyelinases (SMases) (E) were analyzed by either HPLC or ESI-LC/MS/MS systems. Data are means ± SD (n=3). ^*p<0.01 versus vehicle control.