In summary, the significance of our findings resides in the following aspects: (1) it reveals macrophage as an important cell type that contributes to PPARγ suppression of cancer and the anti-tumor effects of rosiglitazone; (2) it identifies Gpr132 as a novel PPARγ direct target gene in macrophages that mediates PPARγ functions; (3) it uncovers Gpr132 as a pro-inflammatory and pro-tumor factor in macrophages, and thus a novel therapeutic target. Here, PPARG is linked to cancer.