Table 1 Structure of each of the 16 non-linear models.

1

Activator

AND

Activator

Activator

2

Activator

AND

Activator

Repressor

3

Activator

AND

Repressor

Activator

4

Activator

AND

Repressor

Repressor

5

Activator

OR

Activator

Activator

6

Activator

OR

Activator

Repressor

7

Activator

OR

Repressor

Activator

8

Activator

OR

Repressor

Repressor

9

Repressor

AND

Activator

Activator

10

Repressor

AND

Activator

Repressor

11

Repressor

AND

Repressor

Activator

12

Repressor

AND

Repressor

Repressor

13

Repressor

OR

Activator

Activator

14

Repressor

OR

Activator

Repressor

15

Repressor

OR

Repressor

Activator

16

Repressor

OR

Repressor

Repressor