Because a low level of PSAP immunostaining was strongly linked to TMPRSS2:ERG fusion, as detected by IHC and FISH (p < 0.0001 each; Supplementary Figure S2), associations with tumor phenotype and prognosis were also separately analyzed in cohorts of ERG-negative and positive tumors (Supplementary Tables S2 and S3). The gene discussed is TMPRSS2; the disease is neoplasm.