For example, Han et al. [50] confirmed that α2δ1 (encoded by the gene CACNA2D1) is a surface marker that marks HCC tumor-initiating cells (TICs), and they identified miR-222 as a tumor suppressor in HCC by controlling the stemness and tumorigenicity of α2δ1+ TICs by directly targeting on pre-B-cell leukemia homeobox 3 (PBX3), which activated the expression of CACNA2D1. This evidence concerns the gene CACNA2D1 and hepatocellular carcinoma.