On the cover: Colocalization of PAF-R and gp170 on MDR-1 K562 cells by confocal analysis. Drug-resistant tumor cells coexpress the platelet activating-factor receptor or PAF and the multidrug resistance 1 gene product P-glycoprotein or gp170 at their membranes. This could be responsible for hypersensitivity to NK lysis and accelerated cell death. Geromin et al. Glycoprotein 170 induces platelet-activating factor receptor membrane expression and confers tumor cell hypersensitivity to NK-dependent cell lysis. 3604.