Cleavage stimulatory factor or cleavage stimulation factor (CstF or CStF) is a heterotrimeric protein, made up of the proteins CSTF1 (55kDa), CSTF2 (64kDa) and CSTF3 (77kDa), totalling about 200 kDa.
The syntrophins are a family of five 60-kiloDalton proteins that are associated with dystrophin, the protein associated with Duchenne muscular dystrophy and Becker muscular dystrophy.