We have identified the SELDI peaks elevated in cancer at m/z 11720 and 11920 as β2-microglobulin from 3 tryptic fragments giving 23% sequence coverage (the 11920 peak is probably a sinapinic acid adduct as this is absent when α-cyano-hydroxycinnamic acid is used as the matrix, data not shown). The gene discussed is HLA-G; the disease is cancer.