Acylpeptide hydrolase (APEH; also known as acylaminoacyl peptidase or oxidised protein hydrolase) is one of the four members of the prolyl oligopeptidase class (POP, clan SC, family S9); it catalyses the removal of N-acylated amino acids from acetylated peptides and has been recently recognised as having a role in the coordinated protein-degradation machinery in Cos-7 cells [15], and in the modulation of cancer progression [16]. This evidence concerns the gene APEH and cancer.