Regarding the expression of SK4 mRNA and proteins in 4 different breast cancer cell lines, including two TNBC cell lines (MDA-MB-231 and MDA-MB-468), and two luminal breast cancer cell lines (MCF-7 and T47D) [28], we found relatively higher expression levels of SK4 mRNA and protein in the TNBC cell lines and reduced expression in T47D cells. The gene discussed is KCNN4; the disease is breast cancer.