RHO and medullary thyroid gland carcinoma: To test whether Rho activity defines the property that differentiates Pa infection in MTLn3 and MTC cells, ExoS translocation was monitored following treatment of both cell lines with Y-27632, an inhibitor of p160 Rho associated protein kinase (ROCK), which is a major downstream effector of Rho GTPase activity associated with tumor invasion (de Toledo et al., 2012).