FIGURE 3.

Characterization of pH_i and Na⁺/H⁺ exchanger activity in melanoma cells with the B-Raf^V600E mutation. A, resting intracellular pH was determined in human melanoma cell lines either with or without the B-Raf^V600E mutation as described under “Experimental Procedures.” Cells with the B-Raf^V600E mutation are indicated. +, indicates the addition of 10 μm EMD87580, a specific inhibitor of NHE1 activity. * indicates significantly decreased from the absence of EMD87580 at p < 0.01. Values are mean ± S.E. of 6–12 experiments. B, proton extrusion rates by various cells lines with or without the B-Raf^V600E mutation. Cells were acidified using ammonium chloride prepulse, and the initial rate of recovery was used with the buffering capacity of cells to calculate proton flux. Values are the mean ± S.E. of 6–8 experiments. ∧ indicates significantly elevated from M19 or MV3 rates at p < 0.01, * indicates significantly elevated from MV3 rates at p < 0.05.