The 52-54 kDa WT1 isoform was expressed only in the estrogen receptor-positive (MCF-7, BT-474, and T47D) but was not expressed in the estrogen receptor-negative cell lines (tumor marker status is shown in Table 1) SKBR-3, MDA-MB-231, MDA-MB-453, and BT-20 (Figure 1(a)). This evidence concerns the gene ESR1 and neoplasm.