A Japanese research team reported that DFAT cells expressed neurotrophic factors, such as BDNF and GDNF, prior to and after transplantation and which likely contributed to the promotion of functional recovery of spinal damage.
If it is one question the it neutral mutation.
which is a mutation that has no effect whatsoever
You may be able to explain this better, but the main idea is the color of the substance would change. Hope this helps!