Fig. 6.

Direct and indirect effects of macrophage USP2 on the insulin-elicited phosphorylation of Akt in C2C12 myotubes. Conditioned media from peritoneal macrophages isolated from Usp2a transgenic (Tg) mice or their control littermates (A, C), or USP2 KD HL-60 cells or control cells (B, D) were collected. (A, B) C2C12 cells were treated with the macrophage-conditioned media for three days. (C, D) The macrophage-conditioned media were added to 3T3-L1 cells. After culturing for 12 h, the media from the 3T3-L1 cells were collected and applied to the C2C12 cells for three days. The C2C12 cells were then stimulated with insulin (200 nM) for 10 min and subjected to Western blot analyses. Values presented are the mean±SD of three experiments. *P<0.05 vs. control cell-conditioned C2C12 cells.