We found that inhibition of GSK3β by lithium chloride, a GSK3β inhibitor, increased H3K27 trimethylation expression in multiple breast cancer cell lines including MDA-MB-231, BT549, MDA-MB-468, and MDA-MB-435S cells and mammary epithelial cells, MCF12A, and conversely, enhancing GSK3β activity using the anticancer drug staurosporine in MDA-MB-468, MDA-MB-435S and BT549 reduced the H3K27 trimethylation level (Figure 1A). The gene discussed is GSK3B; the disease is breast cancer.