When comparing bronchial airway epithelial cell samples from mice with early stage lung squamous cell carcinoma (LSCC) with those of normal mice, CXCL7 gene is overexpressed 115-fold, indicating that CXCL7 is not only a blood biomarker for the diagnosis of non-small cell lung cancer (NSCLC), but also a biomarker for bronchial brush samples (Xiong et al., 2017). Here, PPBP is linked to squamous cell lung carcinoma.