E2 and PRL co-treatment inhibits MCF-7 cell growth and proliferation in low density/ compliant but not high density/ stiff collagen matrices.

<p><b>a)</b> MCF-7 cells were cultured in LD or HD collagen and treated ± E2, ± PRL for 72h. Cells were removed from gels and counted. n = 3. <b>b)</b> MCF-7 cells were cultured and treated as in <b>(a)</b> and lysates were immunoblotted with the indicated antibodies. Representative blots shown. <b>c)</b> MCF-7 cells were cultured as in <b>(a)</b> and treated ± 4-OHT 1h prior to hormone treatment. n = 4. <b>d,e)</b> MCF-7 cells were cultured and treated as in <b>(a)</b>. Gels were fixed and stained for DAPI and Ki-67, and quantified as described in the Materials and Methods (d). n = 3. <b>e)</b> Representative images of DAPI/ Ki-67 are shown in (d). Different letters represent significant differences (p<0.05) among treatments within each matrix condition <b>(a,d)</b> (LD, lower case; HD, upper case) or inhibitor treatment <b>(d)</b> (vehicle, lower case; 4-OHT, upper case). Asterisks indicate significant differences between the same treatments in different collagen densities, *p<0.05; ***p<0.001.