Fold changes in target gene expressions normalized using different reference gene(s). Fold changes in transcript expressions of Egr-1 (A), Integrin alpha 1, ITGA1 (B), Crystallin alpha b, CRYAB (C), in NGF treated samples relative to that of control were normalized by (1) geometric mean of RPL10a/RPL29; (2) geometric mean of RPL19/RPL29; (3) ACTB or (4) GAPDH. Normalization by GAPDH led to significant quantitative underestimations of EGR1 and ITGA1 upregulation and overestimation of CRYAB downregulation. Dotted line represents the 2-fold difference between treatment and control subjects, a cut off commonly used to distinguish significant changes from insignificant ones. Significant differences between fold changes normalized by various reference gene(s) were calculated using the paired Student's t-test. A value of p < 0.05 was considered significant (**p < 0.01; *p < 0.05).
Zhou et al. BMC Genomics 2010 11:75 doi:10.1186/1471-2164-11-75