Figure 4

Intracellular acidification by cis-UCA activates the ERK and JNK signalling pathways. (A.) The 5637 cells were treated with 0-3% cis-UCA at pH 6.5 for 2 h after which the culture medium was changed and the MTS/PMS reagent added to cells. Absorbance (490 nm) was measured hourly up to 4 h (Mean ± SEM; n = 3, representative of two independent triplicate experiments). (B.) The 5637 cells were treated with 2% cis-UCA at pH 6.5. After harvesting, whole cell lysates were prepared, and ERK and JNK activity was monitored by Western blotting against phospho-ERK, ERK, phospho-JNK, and JNK. Actin expression was measured as loading control. (C.) The cells were treated with JNK inhibitor SP600125 or ERK inhibitor PD98059 for 40 min before addition of 2% cis-UCA at pH 6.5 for the following 2 h. Twenty hours later, cell viability was monitored by the MTS assay (Mean ± SD; n = 3).