KRT7 and ovarian serous adenocarcinoma: A recent study on the origin of ovarian cancer (Hu et al., 2020) connected fallopian tube epithelial cell subtypes to intra-tumor heterogeneity in serous ovarian cancer (SOC), and used KRT7 as a marker for secretory epithelial (SE) cells in the fallopian tube as the cell-of-origin for SOC.