Interestingly, whereas this molecular dependence was evident in all BC cell lines and primary samples tested, a comparable tight coupling of SOX2 protein on pAKT activity was not consistently detected in other tumor types (e.g. ovarian and squamous neck carcinoma cell lines), suggesting an involvement of yet unknown tissue-specific factors or even alternative regulatory principles in other cell types (Supplementary Figure 6). Here, SOX2 is linked to breast cancer.