The Tumor-associated macrophages (TAM) are key pieces to the survival and proliferation of free detached tumor cells from the primary tumor to form spheroids in early steps of transcoelomic metastasis, Long and coworkers established an in vitro spheroid formation assay with a co-culture system composed by GDP+F4/80+CD206+TAMs from an isolated of spheroids of ovarian cancer-bearing donor tomatoIysM-cre mouse, mixed with ID8 cells in a medium with matrigel. The gene discussed is MRC1; the disease is neoplasm.