Pasteurella multocida toxin (PMT) is a bacterial protein toxin produced by few P. multocida serotype A and D strains. It acts as an effective mitogen in numerous cell types in vitro. PMT inhibits osteoblast differentiation by activating the Rho/Rho-associated coiled-coil containing protein kinase (Rho/ROCK) pathway. Infections of PMT cause atrophic rhinitis in pigs and by local dermatonecrosis, respiratory disease in cattle and rabbits. PMT is also a pathogenic agent of dermatonecrosis and bacteremia in humans.