Notably, within these early-passage organoids we identified a population fitting our profiling of ERG+ tumor cells, expressing a high level of LE cell markers (KLK3, KLK2, and ACPP) and tumor markers (PCA3, TRPM8, and ERG) (Supplementary Fig. 9a), which we annotated as putative tumor cells. The gene discussed is KLK2; the disease is neoplasm.