TGFB1 and autosomal recessive polycystic kidney disease: Thus, the transcriptome analysis indicates that ARPKD cholangiocytes are less mature, more proliferative, and have a reduced level of expression of mRNAs regulating cell polarity and epithelial cell function, but have increased TGFβ pathway activation, and are more actively involved in collagen fiber generation than control cholangiocytes.