Taking ARPKD, a disease of the focal adhesion complex and the primary cilia due to mutations of fibrocystin (encoded by PKHD1)70, for example, we found that ARPKD renal cystic cells had significantly lower endogenous RA/RAR activity than age-matched control CD cells. The gene discussed is PKHD1; the disease is autosomal recessive polycystic kidney disease.