Distinguishing graded and ultrasensitive signalling cascade kinetics by the shape of morphogen gradients in Drosophila

► A general method is developed for analysing models of two-state reaction-diffusion systems. ► Spatial gradients are computed when such systems are connected via a signalling cascade. ► We show differences predicted by graded and ultrasensitive signalling cascades. ► Our results may be used to infer properties of signalling cascades during Drosophila development.