Moreover, it involves interactions between AHR and retinoic acid signaling, which is another part of the endogenous metabolome.358 Similarly, AHR activation can cause hydronephrosis in developing animals due to hyperproliferation of epithelial cells in the ureter.359 The etiology involves altered expression of EGFR, EGF, and transforming growth factor-α. This evidence concerns the gene AHR and hydronephrosis.