Estrogen modulation of NMM-II-B filaments assembly. A, CaSki cells were shifted for 3 d to steroid-free medium and treated with the vehicle (− Estrogen) or 10 nM 17β-estradiol for 2 d (+ Estrogen). Changes in the assembly (homodimerization) of NMM-II-B filaments were determined in vitro using purified preparations of NMM-II-B filaments in terms of the critical concentration (CC) of NMM-II-B filaments as determined from the x-intersection of the vertical broken lines (initial deflection of the percent nonassembled protein). B, Time effect (left panel), dose effect (middle panel), and specificity (right panel) of estrogen modulation of NMM-II-B filaments assembly. hEVECs were shifted for 3 d to steroid-free medium and treated with the vehicle, 17β-estradiol (17β-E2) for the durations or the indicated doses, or one of the following estrogens (all for 48 h): diethylstilbestrol (DES, 10 nM); estrone (E1, 100 nM); estriol (E3, 100 nM); 17α-estradiol (17αE2, 10 nM); and 17β-estradiol-6-[o-carboxymethyl]oxime-BSA (17β-E2-BSA, 1 μM). Changes in the assembly of NMM-II-B filaments were determined in terms of the NMM-II-B critical concentration. Shown are means ± SD of three to six experiments. Similar effects of 17β-estradiol were also obtained in CaSki cells (not shown). a, P < 0.01–0.04, compared with no treatment with estrogen.