PTK7 and cancer: POSTN has been reported to participate in the epithelial-to-mesenchymal transition, radio-resistance, angiogenesis, and invasion of HNSCC.[33–36] Furthermore, a recent study revealed that fibroblasts secreted POSTN promotes cancer stemness in HNSCC by activating protein tyrosine kinase 7.[37] This result was consistent with our analysis, indicating the key role of POSTN in mediating the cross-talk of tumor cells and tumor microenvironment, and in modulating tumor cell biology.