MST1 and neoplasm: Mammosphere formation assays including both monoculture and co-culture with RON proficient or RON deficient bone marrow-derived macrophages (BMDM) recapitulated several points, including that loss of HGFL in tumor cells impairs mammosphere formation [6], and that addition of RON proficient, but not RON deficient BMDM augments mammosphere formation [17].