During Gt phase, the cell is in resting state and the nucleocytoplasmic index is stable. During the S phase of the cell cycle, DNA replicates, consequendy nucleocytoplasmic index increases due to increase in nuclear volume. During G2 phase, the cell is again stable. During M phase, nucleocytoplasmic index decreases. After M phase or mitosis when the cell divides, nucleoplasmic index returns to normal.