This family consists of several bacterial intracellular growth attenuator (IgaA) proteins. IgaA is involved in negative control of bacterial proliferation within fibroblasts. IgaA is homologous to the E. coli YrfF and P. mirabilis UmoB proteins. Whereas the biological function of YrfF is currently unknown, UmoB has been shown elsewhere to act as a positive regulator of FlhDC, the master regulator of flagella and swarming. FlhDC has been shown to repress cell division during P. mirabilis swarming, suggesting that UmoB could repress cell division via FlhDC. This biological function, if maintained in S. enterica, could sustain a putative negative control of cell division and growth exerted by IgaA in intracellular bacteria.