PTGS2 and neoplasm: To further assess the translational relevance of melanoma and the NSCLC cell-intrinsic ALDH3A1 pathway, we performed ALDH3A1 staining and quantitatively assessed melanoma and NSCLC ALDH3A1 positivity in relation to PD-L1 expression (as markers of oncogenic and immune signals), and COX-2 expression (as marker of tumor-related inflammation) in tumor biopsies obtained from n = 7 melanoma patients and n = 13 NSCLC patients (Figure 8 and Supplementary Tables S4 and S5).