IRS1 and Cachexia: Briefly, the Walker-256 tumour as an experimental model of cachexia shows that its development increases the muscle protein degradation by increasing the proteolysis-induction factor-like – Walker-Factor - (WF) levels, but also decreases the muscle protein synthesis by reducing the insulin level, which was associated with lower activation of IRS-1 in W group, especially after the 14th and 21st day after implant.