These discordant results may be a consequence of a number of differences between in vitro versus in vivo systems, including the time scale of NCOA4 loss, relative dependence on NCOA4-mediated ferritinophagy for iron balance in cell culture models (most of which are tumor-derived cell lines) versus normal tissues, and differences in the iron availability between in vivo growth conditions and cell culture models which are predominantly grown in transferrin-rich serum-containing media. The gene discussed is NCOA4; the disease is neoplasm.