PAK6 and small cell lung carcinoma: Previous studies have shown that PAK6 is highly expressed in various tumors (Huang et al., 2022; Raja et al., 2016; Yang et al., 2020; Zheng et al., 2021), Our findings extend this understanding to small cell lung cancer (SCLC), demonstrating significantly elevated serum PAK6 levels in SCLC patients compared to NSCLC, pulmonary nodule (PN), and normal control (NC) groups (p < 0.01; Table 2).