CXCR4 and lung cancer: Interestingly, PD-L1high lung cancer cell lines were associated with higher expression of certain chemokines such as IL-8 and CXCL5 (neutrophil chemotactic factors), and chemokine receptor such as CXCR1 (IL-8 receptor) while PD-L1low lung cancer cell lines were associated with higher expression of CXCR4 and CXCR7 that are essential for lung cancer progression and angiogenesis (Tables 2 and 3) [38,39].