The PIs are the largest component of the program, continuing to grow with new members each year. Each PI also has a program of research within the scope of the CFG, supported by non-CFG funds. Investigators apply for membership and must have a funded grant within the scope of the CFG, but they are not required to join the CFG to access resources. Several PIs also have CFG-funded bridging grants that are primarily tied to and enable the goals of the scientific cores, for the benefit of all PIs.