In GC cells, down-regulation of miR-21 inhibits cell proliferation and EMT, thereby inhibiting invasion and metastasis of tumor cells,[56,57] while miR-106 has similar biological effects on GC, colorectal cancer and endometrial cancer cells.[58–60] MiR-421 and miR-223 regulates the apoptosis and invasion ability of GC cells by targeting Caspase-3 and Arid1a respectively.[61,62] These 4 miRNAs are also involved in regulating drug resistance of GC cells. The gene discussed is CASP3; the disease is gastric cancer.