To determine whether breast cancer cell lines (MCF-7, T47D, SKBR3, JIMT-1, MDA-MB-231, and HCC-70) express and secrete IL-18, the levels of mature IL-18 (18 kDa) were measured in cell lysates by western blot, and gene expression was quantified by RT-qPCR (Supplementary Figure 1A and 1B). Here, IL18 is linked to breast cancer.