Only modest increases in NIS mRNA expression were detected in tRA- and tRA/H-treated MCF-7 breast cancer cells by the 211123_at NIS probe set. MCF-7 human breast cancer cells were treated with DMSO vehicle, tRA(1 μM) or tRA(1 μM)/H(1 μM) for 12 hours, total RNA was harvested, and NIS mRNA was detected by parallel qRT-PCR and microarray (HG U133 Plus 2.0) experiments. The quantification of hNIS by qRT-PCR was normalized according to the level of GAPDH and the data are presented as a fold change in NIS mRNA over GAPDH control. (A) While qRT-PCR detected 7.0- and 12.6-fold increases in NIS mRNA with tRA and tRA/H treatments, respectively, only 2.1- and 2.4-fold increases were detected by microarray. The mean ± standard deviations of two independent trials are plotted. (B) Signal intensities detected by the 11 individual perfect match probes within the NIS probe set are depicted for two independent trials of DMSO-, tRA- and tRA/H-treated MCF-7 cells. The figure depicts variability in the extent of change in NIS mRNA among all 11 probes with tRA and tRA/H treatment. Fold changes in normalized NIS mRNA levels are also indicated for each individual trial.