Secreted protein that acts as a key regulator of lysosomal function and as a growth factor involved in inflammation, wound healing and cell proliferation (PubMed: 28541286, PubMed: 28073925, PubMed: 18378771, PubMed: 28453791, PubMed: 12526812). Regulates protein trafficking to lysosomes and, also the activity of lysosomal enzymes (PubMed: 28453791, PubMed: 28541286). Facilitates also the acidification of lysosomes, causing degradation of mature CTSD by CTSB (PubMed: 28073925). In addition, functions as wound-related growth factor that acts directly on dermal fibroblasts and endothelial cells to promote division, migration and the formation of capillary-like tubule structures (By similarity). Also promotes epithelial cell proliferation by blocking TNF-mediated neutrophil activation preventing release of oxidants and proteases (PubMed: 12526812). Moreover, modulates inflammation in neurons by preserving neurons survival, axonal outgrowth and neuronal integrity (PubMed: 18378771). [Granulin-4]: Promotes proliferation of the epithelial cell line A431 in culture. [Granulin-3]: Inhibits epithelial cell proliferation and induces epithelial cells to secrete IL-8. [Granulin-7]: Stabilizes CTSD through interaction with CTSD leading to maintain its aspartic-type peptidase activity.