PKD2 and cyst: Because PKD1 and PKD2 are present in primary cilia (Yoder et al, 2002; Pazour et al, 2002b) and cyst formation and growth induced by the deletion of Pkd1 or Pkd2 share several characteristics of cystogenesis in cilia mutants (Davenport et al, 2007; Piontek et al, 2007), we reasoned that loss of Pkd1 or Pkd2 may have resulted in some sort of a structural defect of cilia and/or centrosome/basal body that could be sensed by the centrosomal integrity/mitotic surveillance pathway leading to the activation of p53.