Timing of ERK activation by E
XEs, and XE/E
mixtures. Rat pituitary cells were exposed to BPS (10-14 M), BPA (10-14 M), NP (10-14 M) and/or E2 (10-9 M) over a 60- min time course. Responses to individual XEs (A) and mixtures (B) were measured by plate immunoassay; the pNp signal generated for each well was normalized to cell number (measured by the CV assay). Values are expressed as percentage of vehicle (V)-treated controls. All error bars represent S.E M. The width of the vehicle bar represents a S.E. of ±1.2 (n = 24 over 3 experiments). * = p < 0.05 compared to vehicle (V); # = p < 0.05 compared to 10-9 M E2.