NIS mRNA levels detected by HG U133A oligonucleotide microarray (NIS probe set ID 211123_at) do not vary among breast tumors or normal breast tissue. The Gene Expression Omnibus dataset GSE3744 consists of normalized log2-transformed genome-wide expression of 7 normal breast tissues, 15 normal ER+ breast tumors and 24 ER- breast tumors. NIS and ER mRNA expression are plotted for each individual breast tissue sample and horizontal lines represent mean expression values among normal breast tissues (light gray line), ER+ breast tumors (dark gray line), and ER- breast tumors (black line). Mean ± standard deviation are also indicated. (A) NIS mRNA levels of breast tissues in the GSE3744 Gene Expression Omnibus dataset did not significantly vary among normal breast tissues (mean 5.1 ± 0.42, range 4.5-5.7), ER+ breast tumors (mean 5.4 ± 0.39, range 4.6-6.0) or ER- breast tumors (mean 5.2 ± 0.51, range 4.4-6.4). (B) In contrast, ER mRNA levels for normal breast tissues (mean 10.1 ± 1.56, light gray line; range 7.4-11.9) and ER+ breast tumors (mean 10.9 ± 2.29, dark gray line; range 5.5-13.9) were significantly greater than ER- tumors (mean 4.2 ± 1.6, black line; range 1.9-8.2).