Criteria to define the different TGF- β signaling responses. All responses must exceed a threshold concentration of 10 pM initially to be considered responsive. (A) Sustained responses: The response must reach 90% of the maximal value Opeak within 2 hours and retain 90% of this maximal value until the end of 10 hours simulation. (B) Transient responses: The response must exceed 10 pM and subsequently return to less than 10% of the highest value Opeak within 2 hours of stimulation. The final value Oend must be lower than 1 pM. (C-D) Oscillations: After the initial ≥10 pM peak at least four further peaks must exceed 1 pM in amplitude. Depending on whether the fifth amplitude is less or higher than half the second amplitude we distinguish (C) sustained and and (D) dampened oscillations respectively.