Yoshida et al. reported that serum sIL-2R and the number of CD68-positive macrophages in the tumor microenvironment were positively correlated, and functional studies performed in lymphoma have shown that MMP-9 is largely produced by tumor-associated macrophages (TAMs) and plays an important role in facilitating sIL-2R production [28]. This evidence concerns the gene MMP9 and lymphoma.