Unambiguously identified down-regulated proteins in tumour cells SM5 included: poly(rC)-binding protein 1, proteasome inhibitor PI31 subunit, histone H4, ATP synthase α chain and in the SM7 tumour cell line: coronin-1A, adenosine deaminase, heterogeneous nuclear ribonucleoprotein A/B, 4-hydroxyphenyl puruvate dioxygenase, eukaryotic translation initiation factor 3 subunit 2, peroxiredoxin-2, ADP-ribosylation factor 1, ubiquitin-conjugating enzyme E2 N, actin-like protein 3 and transforming protein RhoA. The gene discussed is UBE2N; the disease is neoplasm.