Cellular metabolism plays a crucial role in maintaining basic cell survival. It provides the necessary energy and building blocks to support the biosynthetic demands of cell proliferation and differentiation. Due to its importance, cellular metabolism is often hijacked by cancer cells to aid in tumourigenesis, proliferation and survival. Arginine is a semi-essential amino acid that serves as a precursor for polyamines and cells become dependent on extracellular sources during rapid growth. Some tumours, known as auxotrophic tumours, display defective arginine synthesis and this is a metabolic vulnerability that can be exploited in the development of antitumour therapeutic strategies. Arginase is an arginine-depleting enzyme that breaks down arginine into ornithine and urea, and is currently undergoing clinical trials as a potential anti-cancer therapeutic agent. Due to a lack of cell cycle checkpoint control, deprivation of arginine in arginine-auxotrophic tumours leads to growth inhibition or cell death whereas deprivation of arginine in healthy cells leads to cell cycle arrest and quiescence. We hypothesise that the combination of arginase along with insulin aids in the uptake of arginase into cancer cells thus preventing cancer cells from utilising both intracellular and extracellular sources of arginine. We showed that the combination therapy improved the uptake of arginase into cells and has a negative impact on the proliferation of cancer cells.