LKB1 serine/threonine kinase interacting protein 1
LIP1 is a protein found in eukaryotes. It represents the N-terminus of a leucine-rich-repeat protein that is implicated in Peutz-Jeghers syndrome. LIP1 interacts with the TGF-beta-regulated transcription factor SMAD4 to form a LKB1-LIP1-SMAD4 ternary complex. Mutations in SMAD4 lead to juvenile polyposis, suggesting a mechanistic link between these two diseases.