ID2

ID2 is a label used in multiple domains as an abbreviation or code, and it does not have a single, universal meaning. Its interpretation depends on the field, organization, and context in which it appears.

In biology, ID2 refers to a gene encoding a member of the inhibitor of DNA binding (ID) family. The ID2 protein is part of a class of basic helix–loop–helix regulators that lack a DNA-binding domain but can dimerize with other transcription factors. By inhibiting these factors, ID2 can influence cell differentiation and proliferation. It participates in various developmental processes and has been studied in contexts such as neural, hematopoietic, and cancer biology. Expression of ID2 is often dynamic, occurring in developing tissues and changing with signaling cues that govern cell fate.

In information technology and security contexts, ID2 is sometimes used to denote a second-generation identity framework or a data element related to identity verification. The term is not associated with a universal standard and its exact meaning can vary by country, organization, or system. When encountered, it typically requires consultation of project-specific documentation or domain conventions to determine its precise role.

In other domains, ID2 may appear as an internal code, model identifier, product name, or project designation. Because of its broad usage, readers should identify the relevant domain to interpret ID2 correctly and rely on source documentation for clarification.

See also: ID1, ID3, inhibitor of DNA binding family.