Hip (HSP70-interacting protein), also known as ST13 (suppression of tumorigenicity protein 13), is one of several co-chaperones that regulate activities of the HSP70 chaperone family (1,2). The homo-oligomeric protein Hip cooperates with HSP70 in protein folding by stabilizing the ADP-bound state of HSP70. Hip directly binds to the ATPase domain of HSP70 when it is converted to the ADP-bound state by proteins of the HSP40 family (3). By collaborating with other positive co-factors such as HSP40