TJP1 and autosomal recessive polycystic kidney disease: ARPKD cholangiocytes also express reduced levels of mRNAs encoding planar cell polarity (DVL2, FZD6) and ductal epithelium/tight junction (CLDN1, CLDH1, TJP1, EPCAM) proteins than control organoids (Supplementary Fig. 4f).