Kim et al. (Kim et al., 2012) reported the top six most highly expressed genes in breast cancer, including STAT3, CTSD, SREBF1, IGFBP5, and DDR1, from 49 signature genes of tumor dormancy based on cancer cell line data and microarray data, which further verified the role of H2BC12 as a potential tumor dormancy marker (Kim et al., 2012). Here, CTSD is linked to cancer.