Myc amino-terminal region. The myc family belongs to the basic helix-loop-helix leucine zipper class of transcription factors, see pfam00010. Myc forms a heterodimer with Max, and this complex regulates cell growth through direct activation of genes involved in cell replication. Mutations in the C-terminal 20 residues of this domain cause unique changes in the induction of apoptosis, transformation, and G2 arrest.