SLC30A1 and neoplasm: The inference is also supported by the previous research of Costello et al.[12] In addition, previous studies reported that ZnT1, a Zn2+ transfer protein that functions to reduce cytoplasmic Zn2+ concentrations, is found to be downregulated in tumor cells, leading to weak Zn2+ efflux capacity of tumor cells,[10, 20] which may be another potential mechanism of selective Zn2+ overloading.