Model for predominant cytoplasmic flow of mRNAs through P-body and stress granule mRNP states. After exit from polysomes, mRNAs are bound by P-body components, forming a P-body mRNP state that could either target the mRNA for decay, or for a return to translation, initially via transition into a stress granule mRNP state. Factors affecting this decision process may include specific mRNA binding proteins (factor “X”) or the presence of a poly(A) tail. Transition into a stress granule aggregate is favored by initial accumulation and mRNP remodeling in a P-body aggregate, though direct mRNP remodeling not involving visible cytoplasmic aggregates may also occur (dashed arrow). Having achieved a stress granule mRNP state, mRNAs would acquire additional translational components (eIF2, eIF3, and 40S subunits) before reentering translation.