ERK activity correlates with the level of EGFR dimerization.
ERK activity was monitored with EKAREV. (A) Time traces of the normalized fluorescence intensity ratio of the acceptor over the donor channel (dots) fitted to the sigmoid function (lines). Sample curves, showing the median values of sigmoid gain for EGFRT654/669A (blue), EGFRY992/1148/1173F (grey), EGFRwt (red), and EGFRT654/669E (green) are shown. (B) Sigmoid gains as indices of the ERK activity. The data are means ± SD. The symbol * indicates significant differences with p < 0.005 calculated using a two sided T-test with unequal variance.