THY1 and amyotrophic lateral sclerosis: Activating transcription factor 3 (ATF3), acting as a neuron growth factor, increases motor neuron survival and maintains axonal connections with muscles by promoting axonal sprouting when overexpressed in motor neurons in an ALS mouse model through ATF3 transgenic mice expressing the ATF3 transgene under the control of the thy1.2 promoter [62].