ATM and sarcoma: In particular, p53-null (p53-KO), which develop mostly sarcomas and T-cell lymphomas24; Atm-null (ATM-KO), which develop T-cell lymphomas25; MMTV-PyMT (polyoma middle-T oncoprotein under the mouse mammary tumor virus promoter), mammary carcinomas26; and Eμ-Myc, B-cell lymphomas27.