miR-203a functions by interacting with a variety of mRNA targets, such as suppressing bladder cancer cell growth by targeting Twist1 (Shen et al., 2018), suppressing the proliferation and metastasis of hepatocellular carcinoma by targeting the oncogene ADAM9 and the oncogenic long non-coding RNA HULC (Iino et al., 2019), suppressing cell proliferation, migration, and invasion in colorectal cancer by targeting EIF5A2 (Wan et al., 2016), and increasing the sensitivity of K562 cells to S2O3 by downregulating the expression of BCR-ABL (He et al., 2013). The gene discussed is TWIST1; the disease is hepatocellular carcinoma.