Indeed, the human HCC1937 breast cancer cell line, harbouring a BRCA1 deletion as well as a hypomorphic BRCA1 allele with a 5382insC frameshift mutation, showed increased chromatin bridges in anaphase and telophase upon olaparib treatment (Fig. 2d), as well as lagging chromosomes (Supplementary Fig. 2H). Here, BRCA1 is linked to breast carcinoma.