Figure 1. Known functions of MK/PTN signaling through their receptors.
Syndecans: Although MK/PTN binds to Sdc 1, 2, and 4, the downstream effectors are unknown. PTN binding to Sdc3 promotes neurite outgrowth and migration [37, 38]. RPTP-β: MK/PTN binding to RPTP-β promotes B cell survival, hematopoiesis, neurite outgrowth, and migration [39, 42]. Integrins: MK can directly interact with α4β1 and α6β1 integrins [50], whereas PTN interacts with αvβ3 [51]; those interactions promote cell migration [50, 51, 58]. Lrp1: MK interacts with α4β1 and α6β1, whereas PTN interacts with αvβ3. Lrp1 drives macrophage/neutrophil haptotaxis [140]. Nucleolin: MK/PTN interaction with nucleolin promotes MK/PTN nuclear localization, cell migration, and survival [58, 67, 68].