PC12 cells, a rat PC12 cell line, were obtained from the Cell Resource Center of the Institute of Basic Medical Sciences, Peking Union Medical College/Chinese Academy of Medical Sciences (Beijing, China). PC12 cells were grown as a monolayer in dulbecco’s modified eagle medium (DMEM) supplemented with 10% horse serum and 5% fetal bovine serum (FBS), 100 U/ml penicillin and 100 μg/ml streptomycin at 37°C in a humidified incubator gassed with 5% CO2 and 95% room air. For neuronal differentiation, PC12 cells were seeded in PLL pre-coated plates and allowed to adhere for 24 h. Following adherence, the culture medium was replaced with nerve growth factor (NGF, 50 ng/ml; New England Biolabs, MA, USA) containing medium. The NGF-containing medium was replaced every other day. Seven days after the supplement of NGF, the NGF-induced differentiation of PC12 cells were determined using immunofluorescence staining with antibodies against the neuron-specific marker microtubule associated protein 2 (MAP2; Supplementary Figure S1).