Secreted protein that functions as cytokine and growth factor and mediates its signal through cell-surface proteoglycan and non-proteoglycan receptors. Binds cell-surface proteoglycan receptors via their chondroitin sulfate (CS) groups. Thereby regulates many processes like inflammatory response, cell proliferation, cell adhesion, cell growth, cell survival, tissue regeneration, cell differentiation and cell migration (By similarity). Inhibits mesoderm formation and promotes neural formation during development (PubMed:9538212). Plays a role in development of the neuromuscular junction (NMJ) (PubMed:9361288). Has antibacterial activity against both Gram-positive and Gram-negative bacteria (PubMed:20308059). Expression at the mid-gastrula stage begins in the neural anlage, and becomes increasingly prominent in the central nervous system and head mesenchyme during neurula stages. Although the mRNA is localized to the developing central nervous system (CNS), the protein is deposited at the neuromuscular junction (NMJ). In the tailbud stage embryo, expressed in the head and tail regions as well as in the CNS. In adults, expression is highest in the brain, eye and bone, with lower expression in the heart and lung. Not expressed in the ovary. Expressed zygotically from the mid-gastrula stage. Belongs to the pleiotrophin family.