ESR1 and breast neoplasm: As shown in Figure 1A, log2 NIS mRNA levels detected among normal, non-lactating breast tissues (mean 5.1 ± 0.42, light gray line) were comparable to breast tumor NIS mRNA levels (ER+, 5.4 ± 0.38, dark gray line, and ER-, 5.2 ± 0.51, black line).