Potential model of HMQ1611 inhibiting breast cancer cell proliferation. Potential model of HMQ1611 inhibiting breast cancer cell proliferation. HMQ1611 regulated ERα expression and membrane-associated E2/ERα pathway, membrane-associated E2/ERα pathway cross-talks with the MAPK pathway, in response to reduced membrane-associated ERα, MAPK activity is suppressed. Meanwhile, inhibition of EGF-induced EGFR phosphorylation by HMQ1611 blocks EGFR activation and its downstream pathways such as MAPKs and PI3K/AKT. Combined blockade of ERα and EGFR pathway leads to reduction of cell proliferation. Yingzhuan Zhan et al. Cancer Prev Res 2012;5:864-873 ©2012 by American Association for Cancer Research