To further define whether the TSPAN18-activated STIM1-Ca2+ signaling pathway was responsible for the role of TSPAN18 in facilitating tumor metastasis, we transfected TSPAN18-overexpressing PCa cells and control cells with STIM1-specific siRNAs or treated them with SKF96365, an inhibitor of Ca2+ influx. Here, STIM1 is linked to neoplasm.