SOX2 and cancer: Furthermore, while the ability of YAP to activate transcription is known to be decreased by phosphorylation via upstream Hippo signaling kinases such as Nf2 and Wwc1 (Yu et al., 2015), it was recently reported that in cancer stem cells, Sox2 represses transcription of the NF2 and WWC1 genes, which in turn increased YAP activity (Basu-Roy et al., 2015).