POU5F1 and polycystic kidney disease: MKRN1, the most studied member of the MKRN family has been shown to participate in a variety of mechanisms such as RNA-II-dependent transcription [17], Oct-4 signaling in mouse embryonic stem cells [18], telomere length homeostasis in cancer cell lines [19], [20], polycystic kidney [21], ubiquitinase activity [22], and p14ARF-associated cellular senescence and gastric tumorigenesis [23].