CNR1 and amyotrophic lateral sclerosis: The same results could not be obtained with analog [18F]RS-126 (Figure 2, Ki = 1.2 nM, >10,000-fold selective over CB1) [23], and in a later in vitro study in post mortem tissue of amyotrophic lateral sclerosis (ALS) patients, a high amount of non-specific binding was observed [24].