To characterize the specific cell populations that contribute to tumorigenesis and are promising anti-cancer therapeutic targets, Lo et al. (2012) previously used CD61/CD49f cell surface markers to isolate these cell populations and reported that the CD61high/CD49fmid population is comprised of CSCs/TICs in erbB-2-overexpressing mammary tumors [44]. Here, ERBB2 is linked to breast cancer.