In 1999, Loeb et al 28 used reverse transcription (RT)-PCR to detect the expression of WT1 mRNA in breast cancer tissues of 31 cases, and found that WT1 expression was high in primary breast cancer (27/31) and low in normal breast tissue (1/20), suggesting that WT1 may act as an oncogene. Here, WT1 is linked to breast cancer.