To test whether PKMYT1 displayed the same selectivity against CCNE1 amplification in tumour-derived cell lines, we next assembled a panel of nine cell lines: three with amplification or gain of the CCNE1 locus (HCC1569, SNU8 and OVCAR3), three with BRCA1 or BRCA2 biallelic mutations that are common in ovarian cancer (SUM149PT, COV362 and DOTC24510), and three that are wild type for CCNE1, BRCA1 and BRCA2 (KYSE30, TOV112D and NUGC3). Here, BRCA1 is linked to ovarian cancer.