POU5F1 and breast cancer: Thus, in the presence of BC-derived exosomes, brain organoids overexpressed the octamer-binding transcription factor 4 (OCT4), known to maintain the stemness features in cancer stem cells (Zhang et al., 2020), as well as the paired box 6 protein (PAX6), which plays an important role in development of human neuro-ectodermal epithelial tissues and sustains cell proliferation in invasive ductal carcinoma of the breast (Xia et al., 2015).