Table 1.

Current knowledge gaps and future directions on Hh in adult lung.

Current Knowledge Gaps	Future Directions
How do non-Hh responsive cells in the lung shape the differential activation of Hh?	Single cell analysis of the lung to examine the spatial distribution of factors that might modify Hh signaling.
How does the Hh ligand get transported from the epithelium to the mesenchyme?	Closer examination of cellular features such as the primary cilia or possibly cytonemes that have been implicated in Hh transduction.
Does the alteration of Hh activation domain occur in other disease contexts?	Examination of how Hh activation domains shifts in other disease such as lung fibrosis and infection.