In addition to CDKN1A, HEB and E2A co-occupy three TSG loci, APC, a haplo-insufficient tumor suppressor, ZMYND11 a chromatin reader and tumor suppressor in breast cancer (115) and CUX1, a homeodomain transcription regulator and haploinsufficient tumor suppressor (116). The gene discussed is TCF3; the disease is breast carcinoma.