UBQLN2 and cancer: It was well known that the proteasome was essential for the survival of cancer cells and proteasome inbititors could exhibit anti-cancer activity by inducing growth arrest and/or apoptosis of cancer cells[73,74].Ubiquilin 2, which was found in the present study as one of possible target-related proteins of arenobufagin and belonged to the proteasome-related protein, was reported to be involved in endocytosis[75].