CTSD and lung adenocarcinoma: In addition to these biomarkers, several novel lung adenocarcinoma-associated proteins have been found using aptamers, such as LMN (lamin) and VIM (vimentin), DEF (neutrophil defensin) and TUB (tubulin), ACT (cytoplasmic actin), CTSD (cathepsin D), CLU (clusterin), NCL (nucleolin), and MUC1 (mucin-1).