释义：
Nerve growth factor (NGF) is a neurotrophin that is endogenously produced during development and maturation by multiple cell types, including neurons, Schwann cells, oligodendrocytes, lymphocytes, mast cells, macrophages, keratinocytes, and fibroblasts. These cells produce proNGF, which is transformed by proteolytic cleavage into the biologically active NGF in the endoplasmic reticulum.
神经生长因子 (NGF) 是一种神经营养因子，在发育和成熟过程中由多种细胞类型内源性产生，包括神经元、雪旺细胞、少突胶质细胞、淋巴细胞、肥大细胞、巨噬细胞、角质形成细胞和成纤维细胞。这些细胞产生 proNGF，通过蛋白水解裂解转化为内质网中具有生物活性的 NGF。