TGFB1 and neoplasm: For brevity, the tumor cells collected with this assay will be hereafter called "migratory tumor cells." With this assay, we recently showed that the invasive properties of the MDA-MB-231 human breast adenocarcinoma cells differ in vitro and in vivo, because of a TGF-β-initiated autocrine CSF1/CSF1R loop that occurs in the tumor microenvironment [16].