Amyloid β precursor-like protein 2 (APLP2) (also known as YWK-II) is a type I transmembrane protein belonging to the amyloid precursor protein (APP) gene family. The APP gene family also contains APP and APLP1 and has been associated with Alzheimer's disease pathogenesis as well as playing a pivotal role in processes underlying normal brain development and postnatal survival. APLP2 is ubiquitously expressed during embryonic development and in most adult tissues, in a pattern largely overlapping with APP. APLP2 is processed by α-, β- and γ-secretase and its cleavage is regulated by insulin-like growth factor 1 (IGF-1), epidermal growth factor, phorbol 12-myristate 13-acetate (PMA), and retinoic acid.

APLP2 has been linked to the development and progression of a number of cancer types, including pancreatic, Ewing's sarcoma, colon, breast, lung and prostate cancer where it is often overexpressed, although significant downregulation of APLP2 is seen in neuroendocrine lung tumours. APLP2 expression is often associated with abnormal growth, migration and invasion in cancer cells. APLP2 expression may increase gradually with the advancement of cancer progression. Different APLP2 splice isoforms may have an influence on cancer development.

The Lysine residue at position 17 of this peptide is isotopically labelled with carbon-13 (6) and nitrogen-15 (2), giving this peptide a mass increase of 8 compared to the unlabelled peptide.