“…For example, administering combinations of growth factors, including insulin growth factor 1 (IGF1) (Duan et al, 2015;Bei et al, 2016), interleukin-6 (IL-6) (Fischer, 2017), ciliary neurotrophic factor (CNTF) (Park et al, 2004;Leaver et al, 2006), and osteopontin (Bei et al, 2016;Anderson et al, 2018), stimulates regeneration of CNS axons. Other studies have shown that modulating distinct genes within the neurons, including signal transducers and activators of transcription factor 3 (Stat3) (Moore and Goldberg, 2011;Luo et al, 2016), histone deacetylase 5 (Hdac5) (Cho and Cavalli, 2012), Cacna2d2 (Tedeschi et al, 2016), Lin28a (Wang et al, 2018;Nathan et al, 2020), phosphatase and tensin homologue (Pten) (Park et al, 2008) or Kruppel like factors (Klfs) (Moore et al, 2009), can enhance neurons' intrinsic axon growth ability. Numerous studies have demonstrated that environmental factors also contribute to axon regeneration.…”