RARB and amyotrophic lateral sclerosis: However, contrasting findings include elevated levels of RARβ and RXRβ in the cytoplasm of motor neurons of the SOD1G93A mutant rats (Jokic et al., 2007) and elevation of nuclear localisation of RARβ in motor neurons of spinal cord tissue from post-mortem ALS patients (Kolarcik and Bowser, 2012).