Hemistepsin A (HsA) is a guaianolide sesquiterpene lactone that inhibits hepatitis and liver fibrosis. We evaluated the effects of HsA on liver X receptor (LXR)-mediated hepatic lipogenesis in vitro and in vivo. Up to 10 M, HsA did not affect the viability of HepG2 and Huh7 cells. Pretreatment with