Among the differentially expressed genes between Tum1 and Tum2/3, Tm4sf1 is a cell membrane protein that was recently considered as a new marker of CSCs in breast cancer, lung cancer, and melanoma (Hong et al., 2022), and is expressed relatively higher in Tum1 (Figure 4A, Supplementary Table S1). The gene discussed is TM4SF1; the disease is breast cancer.