G1 Phase

**Definition:** The period of the CELL CYCLE preceding DNA REPLICATION in S PHASE. Subphases of G1 include competence (to respond to growth factors), G1a (entry into G1), G1b (progression), and G1c (assembly). Progression through the G1 subphases is effected by limiting growth factors, nutrients, or inhibitors.

**Tree numbers:** - G04.144.500.320

**Synonyms:** - Gap Phase 1 - First Gap Phase