Complex sentence: Oncomodulin is a parvalbumin-family calcium-binding protein and a macrophage-derived growth factor, which promotes axon regeneration in retinal ganglion cells and maintains functioning in mouse cochlear hair cells.
Split into simpler sentences: Oncomodulin is a parvalbumin-family calcium-binding protein expressed and secreted by macrophages. Oncomodulin promotes axon regeneration in retinal ganglion cells and maintains functioning in mouse cochlear hair cells.