NOS2 and Insulin resistance: Lumeng et al. reported that ATM isolated from lean animals expressed hallmarks of polarization toward M2 macrophages with IL-10 and arginase expression, whereas in obese animals with insulin resistance, monocyte chemoattractant protein-1 (MCP-1) released from obese WAT caused a shift to M1-polarized ATM with increased TNF-αα and inducible nitric oxide synthase (iNOS) [13].