FOXK2 and neoplasm: The expression level of FOXK2 was indeed upregulated in flow-sorted ALDH+ versus ALDH– cells from primary high-grade serous OC (HGSOC) specimens (n = 5, P = 0.008) and from the cell lines OVCAR5 (n = 3, P = 0.03) and COV362 (n = 3, P = 0.02) (Figure 1, A and B), and in ALDH+ cell–enriched tumor cell spheroids compared with monolayer cultures (Figure 1C) derived from OVCAR5 and COV362 cell lines.