S1PR1 and neoplasm: This combination inhibited growth of E0771 cells (a mouse mammary adenocarcinoma cell line expressing the ER) in vitro and suppressed the expression of S1P signaling-related genes, STAT3 and IL-6, as well as reducing tumor burden in vivo (119), suggesting that the SK1/S1P/S1PR1 axis plays a role in doxorubicin resistance.