Interestingly, Al Emran et al. (24) recently reported a correlation between gain of H3K9me3 marks associated to upregulation of histone methyltransferases SETDB1 and SETDB2 to induction of a DOX-tolerant phenotype in some cancer cell lines, including the SKBR3 breast cancer cell line, suggesting that a similar mechanism could be operating in Hs578T cells. This evidence concerns the gene PRDM9 and cancer.