STAC3 and chronic kidney disease: Mechanisms that control increased production (e.g., IDO1, KMO, KAT, QPRT) and extracellular release of these molecules (e.g., kynurenine, kynurenic acid, NAMPT, quinolinate, NMN, NAM) may be therapeutic targets in CKD (Figs. 3 and 9).