Given that the various in vivo models demonstrate a role for RON in the myeloid compartment (largely attributable to macrophages), the in vitro data support this, as RON/HGFL overexpressing tumor cells co-cultured with RON deficient macrophages do not show a boost to mammosphere formation even when exogenous HGFL is provided. The gene discussed is MST1; the disease is neoplasm.