Deploying parasite profilin on a mission of invasion and danger.

Interleukin-12 (IL-12) is important in inducing Th1 responses during infection with microbial pathogens such as the protozoan Toxoplasma gondii. In this issue of Cell Host & Microbe, Plattner and colleagues describe an engineered Toxoplasma strain that lacks profilin, an actin-binding molecule previously implicated in Toll-like receptor-11-dependent IL-12 induction and now shown to be important in parasite motility and host cell invasion.