ALDH3A1 and melanoma: Consistent with our in vitro results, tissues from either lung cancer or melanoma with a high ALDH3A1 H score (i.e., ≥ 4) showed PD-L1 expression higher than 70%, while samples with low ALDH3A1 expression (i.e., ≤ 3) showed low PD-L1 positivity (5–40%) (Supplementary Table S4).