Figure 2. Reported signal transducers at early (0-24h) stages of 1,25(OH)2D3-induced monocytic differentiation.
1,25(OH)2D3, through an unknown mechanism, induces rapid activation of various MAPKs which leads to an increase in AP-1 activity. Ras-Raf-ERK activation is additionally modulated by KSR-1, which is up-regulated by 1,25(OH)2D3. Activation of ERK1/2 and JNK1 positively regulates cell differentiation, while p38 MAPK α/β and JNK2 have a negative influence. There is also a potential negative feedback mechanism between p38 MAPK and ERK MAPK signal transduction pathways, as ERK activities increase when p38 α/β is inhibited.