In this study, we explore the mechanistic relationship between growth factor signaling and kinase activity that supports the protein synthesis-dependent phase of long-term memory (LTM) consolidation for sensitization of "Aplysia." Specifically, we examine LTM for tail shock-induced sensitization of the tail-elicited siphon withdrawal (T-SW) reflex, a form of memory that requires both (i) extracellular signal-regulated kinase (ERK1/2; MAPK) activity within identified sensory neurons (SNs) that mediate the T-SW and (ii) the activation of transforming growth factor ß (TGFß) signaling. We now report that repeated tail shocks that induce intermediate-term (ITM) and LTM for sensitization, also induce a sustained post-training phase of MAPK activity in SNs (lasting at least 1 h). We identified two mechanistically distinct phases of post-training MAPK: (i) an immediate phase that does not require ongoing protein synthesis or TGFß signaling, and (ii) a sustained phase that requires both protein synthesis and extracellular TGFß signaling. We find that LTM consolidation requires sustained MAPK, and is disrupted by inhibitors of protein synthesis and TGFß signaling during the consolidation window. These results provide strong evidence that TGFß signaling sustains MAPK activity as an essential mechanistic step for LTM consolidation.