HOXB7 and melanoma: Retroviral transduction of PLZF expression in melanoma cells resulted in a more differentiated, less malignant phenotype both in vitro and in vivo [26] which appears to be mediated by inhibition of the Pre-B-Cell Leukemia Homeobox 1 (PBX1) and Homeobox B7 (HOXB7) complex [37].