The MCF-7 Tet-Off/ACSL4 tumor xenografts, the MCF-7 Tet-Off empty vector tumor xenografts, and the MCF-7 Tet-Off/ACSL4 tumor xenografts treated with doxicycline (Figure 3) were isolated, stained with hematoxylin–eosin and analyzed under light microscopy in order to define the histology of the tumors (Figure 3). The gene discussed is ACSL4; the disease is neoplasm.