Quantification of intracellular NADPH levels
NADPH levels were quantified using the high sensitivity NADPH
quantification fluorometric Assay Kit (#MAK216; Sigma Aldrich), as
previously described [32]. The fluorescent reaction product was
quantified with a SpectraMax i3X microplate reader (Molecular Devices,
Sunnyvale, CA) using excitation and emission wavelengths of 535 and 587
nm, respectively.