Carnosic acid and promotion of monocytic differentiation of HL60-G cells initiated by other agents

food preservative with chemoprotective effects against car-cinogens when tested in animals. Recently, we showed that carnosic acid potentiates the effects of 1,25-dihydroxy-vitamin D3 (1,25[OH]2D3) and of all-trans-retinoic acid (ATRA) on differentiation of human leukemia cells. We now examine the mechanisms associated with carnosic acid-induced enhancement of cell differentiation (in subline HL60-G) initiated by 1,25(OH)2D3, ATRA, or 12-O-tetradecanoylphorbol-13-acetate (TPA). Methods: We evalu-ated monocytic differentiation markers (CD11b, CD14, and monocytic serine esterase), cell cycle parameters, and cell proliferation rates after treatment of cells with different agents with or without carnosic acid. We also assessed the abundance of the vitamin D receptor (VDR), retinoid X re-ceptor (RXR)-, retinoic acid receptor (RAR)-, and cel