ID2 (Inhibitor of DNA Binding 2, HLH Protein): ID2 is a protein that regulates cellular functions by inhibiting the binding of basic helix-loop-helix transcription factors. This inhibition plays a crucial role in controlling cell differentiation and proliferation. ID2 is involved in essential developmental processes such as neurogenesis, immune system development, and cellular senescence, and it has also been associated with the regulation of cancer cell growth and metastasis.