YAP1 and Bloom syndrome: Furthermore, the conditional deletion of Sphk1 in fibroblasts reduced BLM-induced Hippo/Yes-associated protein (YAP) 1 expression and the inhibition of SPHK1 activity by PF543, attenuated TGF-β-mediated YAP1 expression, as well as the expression of fibronectin (FN) and α-smooth muscle actin (α-SMA) in lung fibroblasts from wild type mice.