ID4 (Inhibitor Of DNA Binding 4, HLH Protein): ID4 is a regulator that influences gene transcription by controlling cell differentiation and proliferation. It belongs to the ID protein family, which modulates various developmental processes by inhibiting the binding of basic helix-loop-helix (bHLH) transcription factors. ID4 is involved in the development of several cancers, where it can function either as a tumor suppressor or an oncogene depending on the context. Studying ID4 provides important insights into cellular differentiation, stem cell biology, and cancer.