NPPB and cardiac hypertrophy: Using qPCR, we found that the expression of ANP, BNP, COL1A1, and COL4A1 mRNA in cardiomyocytes following COX6A2 knockdown was significantly increased compared with that of the WT cells (Fig. 3D–G), suggesting that the cardiomyocytes developed toward cardiac hypertrophy and fibrosis.