Interestingly, in a mouse model of peritoneal ovarian cancer, based on the intraperitoneal injection of ID8 tumor cells, spheroids formed by peritoneal macrophages and tumor cells, through β2 integrin‐ICAM‐1 interactions, were detectable in the ascites from 3 weeks after ID8 injection.[84] Macrophages present in the peritoneal cavity increased in number almost tenfold along the first 8 weeks after ID8 injection, and switched gradually from expressing M1 (Ccr2, Ifnar, iNOS) to M2 genes (Cd206, arginase 1, Cd163). Here, ARG1 is linked to neoplasm.