Figure 7. Some intracellular signaling pathways are potentially involved in MCP-1 transactivation in response to HOS in ARPE-19 cells. We suggest a possible pathway with p38 MAPK as its cornerstone, with p38 MAPK that can be either activated by MEK and then phosphorylate the transcription factor p53 (green arrows), or activated by PKC and then phosphorylate HIF1α via the PI3K-PDK1-AKT axis (orange arrows). p53 and HIF1α could therefore both induce MCP-1 transcription.