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 chemoattractant concentration, the signaling molecule is transiently activated such that the response magnitudes are dependent on fold changes of the stimulus, not on absolute levels .