The first and clearest evidence for a role of G4 structure in the regulation of gene transcription came from studies carried out on the v-myc avian myelocytomatosis viral oncogene, homolog (MYC), a transcription factor that regulates the expression of a variety of genes and is one of the most prevalent oncogenes found to be altered in human cancer, being deregulated in about 50% of tumors [58]. The gene discussed is MYC; the disease is cancer.