CCNA2 and gastric cancer: CCNE1 amplification may result in the promotion of the transcriptional induction of S-phase-related genes such as cyclin A and accelerate the G1 phase, causing cell cycle dysregulation and contributing to cancerization [16], suggesting that CCNE1 accumulation in the early stage of GC may promote the LN metastasis process via the induction of the G1 phase to the S phase.