Based on the expression pattern of nucleostemin, CD44, CD24 and ALDH-1, the stemness character of the SKBR3 human breast cancer population is similar to that of the 10AT-Her2 cell population, whereas MCF-7 and MDA-MB-231 cells express significantly lower levels of nucleostemin and do not produce detectable levels of ALDH-1. Here, ALDH1A1 is linked to breast cancer.