HAS1 and breast cancer: To investigate HA machinery across mammary tumors, cell-specific gene expression was analyzed within 4T1 (Fig. 5 A) and HC11/R1-LM (Fig. 5B) tumors utilizing a panel of HA-related genes: HA synthesis (Has1-3), HA fragmentation (Hyal1,2), and HA receptors (Cd44, Rhamm, Lyve1).