KLK2 and posterior cortical atrophy: Overall, compared to club cells from normal samples, PCa-club cells exhibited downregulation of genes including lipocalin 2 (LCN2) and a growth-inhibitory cytokine SCGB3A140,41 and upregulation of LTF, AR, and AR downstream members including KLK3, KLK2, ACPP, and NKX3-1 (Fig. 3b), which we hypothesized could be driven by the enrichment of one or more specific club cell states in the PCa samples.