Evaluation of GAPDH and β-actin as internal reference proteins of Skp2 by Western blot
Objective To determine the appropriate internal reference protein for the Western Blot(WB)assay to detect proteins related to S-phase kinase-associated protein 2(Skp2).Methods This study was carried out with several human tumor cell lines.The intracellular Skp2 protein level was down-regulated by transient transfection of shRNA plasmid,and glyceraldehyde-3-phosphate dehydrogenase(GAPDH)and β-actin were used as internal reference proteins respectively for WB assay.The relative expression levels and correlations of GAPDH,β-actin and Skp2 were evaluated.Results When the relative expression level of Skp2 changed,the relative expression levels of GAPDH in human non-small cell lung cancer cells H1299(1.32 × 106±7.86 × 104),human cervical cancer cell HeLa(6.59 × 106±1.79 × 106)and human liver cancer cell HepG2(3.13 × 106±2.87 × 105)all changed significantly(all P<0.05).The correlation results showed that for human non-small cell lung cancer cells A549(R=0.825 8)and H1299(R=0.906 2),and there was a certain correlation between Skp2 and GAPDH expression levels(all P<0.05).Conclusion β-actin is more suitable to be applied as reference protein in WB assay for Skp2 protein.
internal reference proteinβ-actinglyceraldehyde-3-phosphate dehydrogenaseS-phase kinase-associated protein 2relative expression levelWestern Blot