Before revision:  Second, upon a spatially homogeneous temporal increase in the chemoattractant concentration, the signaling molecule is transiently activated such that the response magnitude is determined by the ratio of the change in the input stimuli before and after the increase .
After revision:  Second, upon a spatially homogeneous temporal increase in the input stimulus, the intracellular signaling molecules are transiently activated such that the response magnitude is determined by the ratio of the change in the input stimuli before and after the increase .