GDNF and lung cancer: Four known biomarkers (CHEK2 in both plasma and urine, CDKN1B, PCNA, and THBS1) were identified as false positives (red) in our breast cancer list, and seven (KRAS, GDNF in both breastmilk and plasma, MYCL1 in both blood and serum, CD40LG, CGA, CTAG1A, ERCC6, and HRAS) in our lung cancer list.