Alveolar surfactant is cleared by distinct pathways. Surfactant proteins (SFTPs) are reutilised by type II cells that internalise alveolar phospholipids destined for re-incorporation into LB for secretion or intra-alveolar or extracellular surfactant is degraded. A substantial portion of surfactant is reutilised (25-95%) in type II cells, promoted by SFTPA (the most abundant surfactant protein) via interaction with a high-affinity receptor present on the cell surface. A candidate for the SFTPA receptor detected on type II epithelial cells is cytoskeleton-associated protein 4 (CKAP4 aka p63), a reversibly palmitoylated transmembrane protein (PALM-C100-CKAP4), initially identified in the ER and Golgi apparatus (Bates 2010). SFTPA and CKAP4 seem to enter the cell as a unit since both are found in early endosomes. At what point SFTPA and CKAP4 separate or whether CKAP4 chaperones SFTPA to the lamellar body is currently unknown. The receptors for the other surfactant proteins (SFTPB, C, D) that are also recycled are not yet identified.