Peter Pan (PPAN) was initially identified in Drosophila melanogaster. PPAN is highly conserved and essential for maintaining growth and survival []. Human PPAN localizes to nucleoli and to mitochondria. It can shuttle between the nucleus and the cytoplasm in response to nucleolar stress and apoptosis induction []. PPAN knockdown has been linked to mitochondrial damage and stimulates autophagy []. The yeast homologues of PPAN, Ssf1 and Ssf2, are nucleolar ribosome biogenesis factors required for maturation of the large ribosomal subunit [].
