TARDBP and amyotrophic lateral sclerosis: In accordance with previous characterizations of the insoluble protein fraction from ALS brains a strong reaction at 25 kDa was detected in motor and prefrontal cortex urea fractions, suggesting that CTFs were present in addition to full‐length TDP‐43 at 43 kDa (1, 5, 6) (Figure 1B).