For these studies, cell migration and invasion of breast cancer cell lines MDA-MB-468 and MDA-MB-231 was measured following siRNA inhibition of SOX11, whereas the ER-positive cell line, MCF7, which typically demonstrates low levels of motility and invasion, was transduced with a viral vector encoding the SOX11 cDNA under the control of a tetracycline-inducible promoter to produce overexpression of SOX11 upon the addition of doxycycline (DOX). The gene discussed is ESR1; the disease is breast cancer.