CFTR and myopathy: We also tested the drug 4-phenylbutyric acid (4-PBA), used for the treatment of urea cycle disorder diseases, which has also been proposed to act as a chemical chaperone for diseases involving misfolded missense mutants (Kolb et al., 2015), such as the Ryanodine Receptor (RYR) (Lee et al., 2017) and the CFTR Δ508 mutant (Rubenstein et al., 1997; Rubenstein and Zeitlin, 1998), and an ER-stress reducer improving outcomes in amyotrophic lateral sclerosis (ALS) (Paganoni et al., 2020) and myopathies (Zito, 2019).