Before revision:  We used our methodology to revisit O'Shaughnessy et al.  tunable synthetic MAPK cascade, in which they claim to have found a new source of ultrasensitivity: ultrasensitivity generated de novo, which arises due to cascade structure itself.
After revision:  We used our methodology to revisit O'Shaughnessy et al. to study a tunable synthetic MAPK cascade, in which they claim to have found a new source of ultrasensitivity: ultrasensitivity generated de novo, which arises due to cascade structure itself.