CCL21 and head and neck squamous cell carcinoma: Derived from 12 chemokine gene signatures [13, 14] and 9 marker genes [6], we proposed a novel gene signature composed of 13 chemokine genes (LAMP3, CCL2, CCL3, CCL4, CCL5, CCL18, CCL19, CCL21, CXCL9, CXCL10, CXCL11, CXCK13, CXCR4) to specifically evaluate HNSCC TLS at the transcriptomic level from the dataset of TCGA (HNSCC) (Fig. 1A).