PLAUR and head and neck squamous cell carcinoma: Previous analyses of head and neck squamous cell carcinoma (HNSCC) cell lines that proliferate in vitro, but do not proliferate upon seeding metastatic sites in vivo, have suggested downregulation of uPAR, or upregulation of TGFβ-II/TGFβR-III signaling, as a cause of a low ERK:p38 signaling ratio, which in turn upregulates the transcriptional repressor DEC2 and downregulates the transcriptional activator FOXM1 [69, 70].