rac

Rac is a term that can refer to several distinct concepts across different domains. In English-language usage, Rac most often appears as part of acronyms formed from the letters R, A, and C. The best-known example is the Royal Automobile Club, commonly abbreviated RAC, a historic British motoring organization that has provided roadside assistance, insurance, and motoring services since the late 19th century. The RAC Foundation is a related research body focused on transport policy. Other organizations in various countries have used the same initials, so the exact meaning depends on context.

In science, Rac denotes a subfamily of small GTPase proteins in the Rho family, including Rac1, Rac2, and Rac3. These proteins act as molecular switches that regulate the actin cytoskeleton, affecting processes such as cell movement, shape, and signaling pathways. The term appears frequently in molecular biology and biochemistry literature to refer to these signaling molecules and their pathways.

As a proper name, Rac can be a surname or given name in some cultures. In certain languages, rac or related forms may have independent meanings beyond a personal name. For example, in Romanian, rac means crab, a usage that appears in language-specific dictionaries and phrases.

Because Rac is not a single fixed entity, its meaning varies with capitalization, field, and region. The article highlights the main senses without proposing a single definition.