SHH and amyotrophic lateral sclerosis: Our data also indicate that the lowest concentration of TNF-α inducing any meaningful decrease in light output in both cell lines is around 5–25 ng/ml, which is much higher than the concentration measured in ALS CSF (13.48 ± 5.56 pg/ml or 0.013 ng/ml), which could explain the absence of any correlation between Shh-LTII assay and TNF-α levels in CSF.