Feed forward motif subtypes: coherent and incoherent. In a feed forward (FF) motif, the interaction between the master and intermediate regulators (named S and y, respectively) modulates the response of the target component, z. In a type 1 coherent FF motif (a), both S and y are activating signals, while y is a repressing signal in a type 1 incoherent FF motif (b). Other --less frequent-- subtypes have been reported .
Domedel-Puig et al. BMC Systems Biology 2010 4:18 doi:10.1186/1752-0509-4-18