The RREB1 (ras responsive element binding protein 1, a.k.a. HNT) gene is located in 6p24.3 and encodes a zinc finger transcription factor. The MYB (MYB proto-oncogene, transcription factor, a.k.a. c-myb) gene is located in 6q23.3 and encodes a transcription factor that is implicated in proliferation, survival, and differentiation of hematopoietic progenitor cells. Overexpression of the RREB1 protein was detected in prostate cancer and in a medullary thyroid cancer cell line. RREB1 is suggested to play a role in Ras and Raf signal transduction in medullary thyroid cancer. MYB has been found to be amplified in a variety of human cancers. In pancreatic cancer, MYB amplification was mainly found in advanced and metastatic tumors. In breast tumors from BRCA1 germline mutation carriers, MYB amplification was observed in 29% of the cases and resulted in overexpression of the MYB protein. Moreover, duplication of the MYB gene occurs in 8.4% of individuals with T-cell acute lymphoblastic leukemia (T-ALL).