While the discrepancy between immunohistochemistry and mRNA level data can be explained by the difference in the patient populations and the data analysis setup, it is also possible that technical artifacts related to the unspecific binding of RET antibodies to breast biopsies led to the overestimation of GDNF/GFRɑ1/RET role in the breast cancer. The gene discussed is GDNF; the disease is breast carcinoma.