CXCR1 and head and neck squamous cell carcinoma: For the further understanding of the expression profile of CXCRs in HNSCC, based on 502 HNSCC samples and 44 healthy control samples from the TCGA database, Perl software and the limma package were utilized to obtain mRNA expression data of CXCR members (CXCR1–7) and analyze the differentially expressed CXCRs. The differential gene expression of CXCRs in the HNSCC samples, as well as normal tissues, was displayed in the heatmap generated by the pheatmap package (Fig. 1B).