LEFTY1 and prostate cancer: Notably, left-right determination factor 1 (Lefty1), an inhibitor of the embryonic Nodal-signaling pathway whose reactivation is associated with tumor progression and the growth of prostate cancer cells [29], but not Lefty2, was up-regulated conspicuously (77.50-fold) following exposure of the cells to luteolin (Table S2 and Fig. S4A).