original_query: What factors are responsible for the upregulation of BDNF and p75 in motor pathway Schwann cells?
query: What factors are responsible for the upregulation of BDNF and p75 in motor pathway Schwann cells after axotomy?
answer: The provided text mentions that denervated motor Schwann cells upregulate BDNF and p75, but it doesn't specify the exact factors responsible for this upregulation.  Further research is implied to be needed to fully understand this process.