Figure 2.

Effect of pH_e on invasion rates of resistant and sensitive cells. In vitro invasion assay using a Boyden chamber coated with Matrigel. Fluorescently labeled cells were measured every 6 hours for 48 hours for invasion through Matrigel layer. Data shown is the result of two biologic experiments (n = 6/sample) normalized to wells lacking serum attractant (n = 2/sample). Data is presented as the mean difference in the rate of invasion of cells cultured in pH 6.8 and cells cultured in pH 7.4 ± SD. The rate of invasion of sensitive cells increases in pH 6.8 compared to resistant lines. *P < .05; **P < .005. _R, resistant; _S, sensitive.