BDNF and amyotrophic lateral sclerosis: Furthermore, application of adenosine A2A receptor agonist CGS21680, a drug that phosphorylates TrkB.FL in motoneurons, regardless of the presence of BDNF or TrkB.T1, slowed the onset of ALS, similar to TrkB.T1 deletion in mice, supporting the concept that increased TrkB.T1 prevents BDNF stimulation through inhibition of TrkB.FL activity [99].