ATP-binding cassette (ABC) (3) transporters are multispan membrane proteins that promote either the active uptake or efflux of specific substrates across various biological membrane systems (e.g., ABCB1) (1,2) or function as regulatory molecules, such as ABCC7 (CFTR) (3, 4), ABCC8 (SUR1) (5), and ABCA1 (6).
A calibration curve with 50, 25,12.5, 6.25 ng of HepG2 total RNA was created for all ABC transporters except ABCA6, ABCA8, ABCA9, ABCA10, ABCB11, ABCC1, and ABCC7. These molecules are not expressed in HepG2 cells; therefore, the calibration curves were created from testis cDNA in a similar manner.