SLC4A4 and neoplasm: Almost one-third of PTCs (33.3%, 16/48) presented a low SLC4A4 protein expression in tumor tissue compared with the adjacent normal thyroid tissue; 93.7% (15/16), 75.0% (12/16), and 81.2% (13/16) of these PTCs with low SLC4A4 presented capsular invasion, extra-thyroid metastasis, and high UIC, respectively, the percentage was significantly higher than that of the unchanged SLC4A4 expression group [54.2% (13/24), 33.3% (8/24), and 37.5% (9/24), P all < 0.05].