The Myc family represents nuclear transcription factors that contribute significantly to cellular proliferation, differentiation, apoptosis and transformation. The myc famliy of cellular oncogenes includes c-Myc, N-Myc, L-Myc, S-Myc and B-Myc. Members of this gene family activate transcription as part of a heteromeric complex with a number of interacting partners, including members of the Max and Mad families. The Myc-Max heterodimers directly upregulate gene expression through specific binding to the sequence CACGTG. Alternatively, c-Myc mediates gene repression by inhibiting the DNA binding protein Miz-1, which functions to inhibit cell growth. Mnt and Mlx regulate Myc activity by forming heterodimers with Max or Mad, respectively, to suppress Myc-induced transcriptional activation.