Figure 3

Calibration of a Western blotting technique for the determination of XIAP using a GST–XIAP protein standard. The fusion protein diluted in MDA-MB-231/X-G4 lysate was analysed within a concentration range of 0.06–135 pg μg⁻¹. Lanes are identified as follows: GST–XIAP (pg μg⁻¹) at 135, lane 1; 110, lane 2; 80, lane 3; 55, lane 4; 28, lane 5; 5.5, lane 6; 2.8, lane 7; 0.55, lane 8; 0.28, lane 9 and 0.06, lane 10. Also included on the blot are the XIAP-deficient cell line MDA-MB-231/X-G4, lane 11; the low QC cell line SF268, lane 12 and the high-QC cell line HeLa, lane 13. The blot was also probed for GAPDH, which acted as a housekeeper protein.