In a study in mice, researchers have identified genes associated with the dramatic transformation of the mammary gland in pregnancy, breastfeeding, and after breastfeeding as it returns to its resting state. Their results form the most detailed atlas of genetic expression ever produced for the adult developmental cycle of the mammary gland. The study also found that genes associated with postpartum breast cancer become active immediately after weaning in various cell types - including in fat cells, which have previously been overlooked as contributors to breast cancer linked to childbirth. We’ve found genes associated with postpartum breast cancer acting in cells that have been similarly overlooked. Reference: Hanin, G et al: ‘Dynamic Allelic Expression in Mouse Mammary Gland Across the Adult Developmental Cycle.’ Nucleic Acids Research, September 2025.