One encodes the well studied mitotic regulator Pin1, which isomerizes phosphorylated Ser/Thr-Pro motifs [9] and thereby is involved in a variety of cellular processes and conditions such as cell cycle regulation, cancer and Alzheimer's disease [10]; the other, the Par14/PIN4 locus on chromosome Xq13.1, gives rise to two protein species, Par14 and Par17 [8]. Here, PIN4 is linked to cancer.