IGF1 and Hepatic fibrosis: The microHO system was also used to examine the effect of other agents that had been directly or indirectly implicated in the pathogenesis liver fibrosis: 5 cytokines — IL-4 (23), IL-6 (24), IL-13, IL-33 (25, 26), and TNF-α (27) — and 3 growth factors — insulin-like growth factor (IGF-1) (28), VEGF (29), and CCL3 (30).