FGF18 and ovarian cancer: In addition to PAX8, COPA complemented with pan-cancer analysis prioritized eight other lineage-restricted outliers (CDH6, CLDN16, FGF18, FOLR1, SLC34A2, SOX17, SPON1, WNT7A) displaying largely confined gene expression in ovarian cancer cell lines (Figure 1D; Figure 1—figure supplement 2A) and tumor specimens (Figure 1E; Figure 1—figure supplement 2B).