MAPK3 and sarcopenia: These effects seem to be mediated via neurones (in the hypothalamus and area postrema and nucleus tractus solitarius of the brainstem) that regulate appetite [15], and ERK1 and 2, neuropeptide Y and melanocortin signalling [16], confirming the role of protein-wasting and sarcopenia in contributing to worsening 6-min walking distances.