Fig. 1.

Inhibition of 3T3-L1 preadipocyte differentiation by pigment epithelium-derived factor (PEDF). Differentiation was induced by 0.5 mM isobutylmethylxanthine, 1 μM dexamethasone, and 1.67 μM insulin (MDI) in postconfluent 3T3-L1 preadipocytes, as described. A: schema indicating that PEDF (10–100 nM) was added on days 0, 3, and 5 during differentiation. B: intracellular lipid was stained by Oil Red O on day 7. B, a: nondifferentiated cells; B, b: MDI; B, c: MDI + 10 nM PEDF; B, d: MDI + 100 nM PEDF. C: quantification of lipid content by spectrophotometer. D–F: expression of adipocyte marker proteins, adipocyte fatty acid-binding protein (aP2; D), adipose tissue triglyceride lipase (ATGL; E), and hormone-sensitive lipase (HSL; F) on day 7 by Western blot analysis. D–F, top: representative blots. D–F, bottom: quantification by densitometry. Results represent 3 independent experiments. Values were expressed as means ± SD. ‡P < 0.01 vs. nondifferentiated cells; *P < 0.05, **P < 0.01 vs. MDI (ANOVA).