Murine mammary carcinoma 4T1cells are highly tumorigenic and can spontaneously metastasize from the primary tumor (i.e., mammary gland) to distant sites such as lung, brain, and bone.22 We observed that metastatic foci in lung were strongly stained with TBXAS1 (Fig. 4a). The gene discussed is TBXAS1; the disease is neoplasm.