Obviously, this significant structural and functional diversity makes the Id proteins a challenging topic of research; however, the successful work done so far encourages to continue the exploration of the biology and structure of these intriguing protein regulators, with the aim to understand and solve controversial data, to answer still open questions, to further validate them as targets for tumor diagnostics and therapy, and to develop drug-like molecules for their detection and inhibition in vivo. This evidence concerns the gene ID1 and neoplasm.