1. To avoid getting false positive paths.
2. Because glnR is autoregulated, knocking it out will not lead
    to a much lower expression than in the reference.
3. Because repression has been inactivated by the deletion, but
    array binding has not.

4. glnA -> guaA and tnrA->yurJ differ from the biological network
5. Because they are in an operon
6. Because the have different signs, we cannot determine which is true
7. The double tnrA glnA mutant. If nrgA increases in transcription
    glnA binds nrgA directly. Otherwise it is via TnrA.
8. There are two loops with opposite signs: GlnA-GlnR versus
    GlnA-TnrA. They compete with each other.