Cell-counting factor that limits the maximum size of the multicellular structure during aggregation. Monomer (By similarity). Component of the counting factor (CF) complex, which includes cf60, cf50, cf45-1 and ctnA. Expressed in vegetative and early developing cells. Increases at 2.5 hours of development, and then decreases slightly. At 10 hours, there is a strong decrease followed by a almost complete decline at 25 hours. Formation of large groups. Belongs to the glycosyl hydrolase 25 family.