Closer examination of lineage-defining genes for ARPC (AR, FOXA1, KLK3, and NKX3–1) and AVPC (SYP, ASCL, NEUROD1, MYCN, SOX2 and DLL3) demonstrated that a subset of AVPC (specifically, transformed with small cell features) expressed high levels of NEUROD1 and MYCN exclusive of neuroendocrine feature-positive prostate cancer (NEPC) and most de novo AVPCs (Fig. 2D). The gene discussed is KLK3; the disease is prostate cancer.