Funding Opportunity RFA-GM-13-003 from the NIH Guide for Grants and Contracts. The purpose of this Funding Opportunity Announcement (FOA) is to diversify and extend the scope and capabilities of currently funded NIGMS R01 and R37 projects for studies on macromolecular interactions and their relationship to function in cells. This FOA solicits competitive revisions (formerly called “competing supplements”) of currently funded NIGMS grants specializing in the analysis of molecular systems and mechanisms in live organelles, cells, tissues, or organisms. Applicants may increase their budgets to extend the scientific scope of their projects or to add new approaches that enhance their capabilities for research on macromolecular interactions in cells. Collaboration is not a requirement of this initiative, but applicants may request support for collaboration (including subcontracts) with investigators who have complementary expertise Support for access of modestly funded laboratories to experimental approaches and research objectives that are otherwise financially out of reach is one priority of this FOA.