The observation that the treated mice also had increased numbers of white blood cells and lymphocytes, as well as increased spleen size, weight and white pulp area (Additional file 1: Figure S1), suggested that PAK1 might affect the immune response to CRC, and prompted us to determine the effect of inhibition or depletion of PAK1 on the immune response to tumour development in an orthotopic intestinal tumour model with a functional immune system. Here, PAK1 is linked to colorectal carcinoma.