MAPT and amyotrophic lateral sclerosis: HDAC6 also plays an important role in the ubiquitin–proteasome system (UPS) and autophagy–lysosome system (ALS) (Van Helleputte, Benoy, & Van Den Bosch, 2014), both of which are known to be responsible for tau degradation (Lee, Lee, & Rubinsztein, 2013).