Model of the proposed actions of rIL-1β on gene expression and physiology of muscle cells in vitro . rIL-1β is recognised by its receptor and an accessory protein, this then sets off a signal cascade resulting in the activation of NFκβ and JUN which in turn result in changes in gene expression and physiology. The proposed changes in physiology are shown in black. Green arrows show a positive effect on this aspect of physiology and red arrows show a negative effect. A sample of genes related to each aspect of physiology is shown in either red (up regulation) or green (down regulation).