GCLC and Cachexia: By contrast, systemic effects are unlikely to contribute to the lack of weight gain and the reduced life expectancy since: (i) serum levels of Il-6 were below detection levels, (ii) expression of important cytokines, which could cause cachexia or other systemic abnormalities was not increased in the skin of the mutant mice, and (iii) Gclc expression was not affected in tissues where the K5 promoter is not active, such as liver and kidney.