Biomedical Engineering Reference
In-Depth Information
1000
1000
A
B
100
100
10
10
1
1
0
0
0.05
0.05
0.1
0.1
0.15
0.15
0.2
0.2
p
1
1
C
0.1
0.1
0.01
0.01
0
0
0.05
0.05
0.1
0.1
0.15
0.15
0.2
0.2
p
Figure 3.14.
A: The ratio of
A
at the front and the back (A), the value of
A
at
the front (B) and the value of
A
at the back (C) as a function of the steepness of
the gradient parameterized by
p
. The curves are normalized by the activity of
A
for
a uniform field.
As already mentioned, it is not possible at this stage to definitively decide
whether or not this modeling approach is correct. This effort was motivated by
focusing on some subset of the existing data - lack of perfect adaption, limited
hysteresis, switch-like fluorescence patterns, transient dynamics in which the
initial excitation is roughly uniform - and by ignoring other aspects - detailed
molecular interaction, the spontaneous emergence of patches, the difference
between cells with and without Latrunculin treatments (which interfere with
actin polymerization), and any coupling between actual cell motion and the
signaling pathway. Other models adopt a different set of assumptions and
thereby come to different conclusions about how the processing could be oc-
curring. Some models stick to the level of abstraction that we have utilized,
whereas others try to be much more explicit about the components. Most
importantly, all models make specific semi-quantitative predictions that can
be tested for their accuracy. Progress will emerge via combining new experi-
