Changes in calcium responses elicited by physiologic estrogens (PE) and xenoestrogens (XE), alone and in combination. The level of Ca [compared to the pretreatment baseline (B) measurement for each assessed cell] was measured by Fura-2 imaging in cells treated with 10 pM E2, E1, or E3 or different 10 pM alkylphenols (EP, PP, OP, NP, or BPA), or physiologic estrogen and xenoestrogen combinations. (A-C) % of cells responding to estrogens; (D-F) changes in accumulated intracellular calcium levels; (G-I) changes of calcium oscillation frequency. Note - some baseline measurements (D-F) were too low to show up as bars on the graphs. * = p < 0.05 compared to control cells. # = p < 0.05 compared to E2, E1, or E3 alone.