Disclosed are proteinaceous molecules corresponding to an acetylation site and their use for inhibiting or reducing the nuclear localization of a nuclear localizable polypeptide, such as PD-1, PD-L1 and PD-L2. This invention also relates to the use of the proteinaceous molecules for altering at least one of (i) formation； (ii) proliferation； (iii) maintenance； (iv) epithelial to mesenchymal cell transition (EMT)； or (v) mesenchymal to epithelial cell transition (MET) of a PD-1-, PD-L1- or PD-L2-overexpressing cell, and for treating or preventing a cancer in a subject.
