tokens: In a PC12 cell mutant that is deficient in protein kinase A activity ( AB .11 ) , all three differentiating agents were unable to down-regulate nrg-1 mRNA .
folded_tokens: in a pc12 cell mutant that be deficient in protein kinase a activity ( AB .11 ) , all three differentiate agent be unable to down-regulate nrg-1 mrna .