Fig 4. Effect of pH on NaCl-dependent ³²Pi transport in MDA-MB-231.

Intact cells (5 x 10⁴ cells/mL = 1.45 mg protein/mL) were incubated for 1 h at 37°C in a reaction mixture containing 116 mM NaCl or 116 mM choline cloride, 5.5 mM Glucose, 5.4 KCl, 0.8 mM MgCl₂, 0.1 mM KH₂PO₄, 2.5 μCi/nmol ³²Pi and 10 mM HEPES, 15 mM Tris, 15 mM MES with pH ranging from 6.4 to 9.2 (A). In these pH ranges, the cells remained viable throughout the experiment according CellTiter 96® AQueous One Solution Cell Proliferation Assay (MTS) (B). These results are the means ± SE of at least 3 experiments, with different cell suspensions.