**5.3.83 Tretinoin (all-***trans* **retinoic acid)**

Tretinoin is the all-trans form of retinoic acid. It has various effects in the nervous system, including neuroprotection and neuroregeneration (for review, see (Lee et al., 2009)).

In a riluzole add-on phase II study (NCT00919555), tretinoin is currently evaluated in combination with pioglitazone.
