Immunogen sequence: QYVEPENVTI QCDSGYGVVG PQSITCSGNR TWYPEVPKCE WETPEGCEQV LTGKRLMQCL PNPEDVKMAL EVYKLSLEIE QLELQRDSAR QSTLDKEL; Positive Samples: A-549, HepG2, HL-60. There are 3 variants of Complement component 4 binding protein (C4bp), which is compos