The Torso signaling pathway is best characterized in the formation of Drosophila embryonic termini, controlled by the localized activation of Torso (tor) receptor tyrosine kinase by trk. Torso signaling has also been shown to regulate larval processes via Ptth activation of tor. The Torso signaling pathway acts via the canonical Ras/Raf/MAP kinase cascade. (Adapted from FBrf0157176 and FBrf0242089.)