Over the last few decades, increasing numbers of studies have shed more light on specific surface biomarkers of CSCs in lung cancer, including CD44 [8], CD133 [9], aldehyde dehydrogenase 1 (ALDH1) [10], C-X-C chemokine receptor type 4 (CXCR4) [11], and ABCG2 [12]. Here, CXCR4 is linked to lung cancer.