Cover figure courtesy of Papayannopoulou et al, "Anti-VLA4/VCAM-1Induced Mobilization Requires Cooperative Signaling Through the kit/mkit Ligand Pathway." A functional cooperativity and signaling from the membrane-bound kit liquid/c-kit pathway is critical for the mobilizing effect. However, the sequence of the steps that lead to this effect have not been worked out. 2231