Proposed model for Shroom3 involvement in LR patterning. Flow diagram illustrating key interactions in early embryonic LR development. Nodal is expressed asymmetrically at the left of the node (mouse), gastrocoel roof plate (Xenopus) or Kuppfer's vesicle (zebrafish), followed by asymmetric Nodal expression in the left lateral plate mesoderm. Pitx proteins bind the Shroom3 promoter to activate expression. Studies from animal models also suggest a role of cytoskeleton-driven polarity in LR asymmetry establishment. LR, left-right; TF, transcription factors.