USP22 and ovarian cancer: The NUDT5-dependent expression of known EMT and CSC genes and of new cancer driver genes (FOCAD and USP22), which also predict a poorer overall outcome in patient datasets, strongly indicate that any future drug discovery focusing on an ATP-specific inhibitor of NUDT5 would be potentially beneficial for the treatment of cancers, including breast and ovarian cancer; in reducing side effects; improving patient health and lifting economic burden.