PIGR and autosomal dominant polycystic kidney disease: Van Den Berg et al. (2002) showed that IL-4 increases intracellular trafficking of proteins in glomerular visceral epithelial cells. Olsan et al. (2015), using human autosomal-dominant polycystic kidney disease tissues, showed that STAT6 pathway activation induces an increase in renal pIgR, which is involved in renal cell IgA transport.