SLC7A5 and amyotrophic lateral sclerosis: In addition, a previous study on ALS model cell lines reported that [14C]citrulline was mediated by Slc7a5/LAT1 transporter In a similar manner, the roles of essential amino acids such as tryptophan in both the BBB and ALS model cell lines have been studied, and the findings suggested that LAT1 was also involved in the transport of [3H]tryptophan [69].