Figure 4.

Effects of major coffee constituents and roasting levels on KRAS expression in Caco-2 cells. (A) Cells were treated with major coffee constituents (caffeine, caffeic acid, chlorogenic acid, and trigonelline) at 100 µM for 24 h, and the KRAS expression was monitored by western blotting. Cells were treated with coffee brewed from different roasts at concentrations of 2.5 and 5% for 24 h, and KRAS protein and mRNA levels were analysed by (B) western blotting and (C) quantitative polymerase chain reaction. *P<0.05 and **P<0.01 vs. 0%. KRAS, KRAS proto-oncogene, GTPase; IB, western blotting; Cntl, 0.1% DMSO control.