text: For example, corr-4a is a bisaminomethyl bithiazole compound that promotes maturation of Phe508 CFTR but shows little rescue of a mutant dopamine receptor 4 (Pedemonte et al., 2005), whereas the thiazole derivative corr-2b and the pyrazole derivative VRT-532 also promote maturation of Phe508 CFTR but show little or no rescue of a P-gp processing mutant (Wang et al.