Fig. 5. ECAR increases in response to increasing endogenous and exogenous EGF. (A) Cells lacking EGF expression were grown in transwells and placed in a cytosensor. Once a baseline ECAR was established, the cells were challenged with an addition of exogenous EGF, 7 nM (
) or 0.1 nM (
). The reported ECAR is normalized to the baseline signal that was set to 0 for clarity. (B) Cells were induced to secrete ligand at a steady state rate of 0 (), 45 (), 400 (
), 700 (
), 1300 (
), 3600 (
) moleculesxcell-1xminute-1 using tetracycline and a ligand-release inhibitor. The cells were placed on the cytosensor and once a baseline was established, they were challenged with 40, 20, 5, 2.5, 1.2, 0.6, 0.3, 0.15, 0.08 ng/ml EGF. The maximal change in ECAR, normalized to baseline, was recorded as a function of the challenge concentration. The error bars represent the s.e.m. of three experiments in duplicate.
