LDHA and breast cancer: The frequencies of tumor formation for cultured ALDH+ cells (1 in 53 for monolayers, 1 in 1 for mammospheres) were significantly higher than that of ALDH+ cells sorted from BC-007 xenografts without culture (P <0.001; P <0.001, respectively; Additional file 1: Table S5) but there was no significant difference between the monolayer- and mammosphere-derived ALDH+ cells (P = 0.3).