Neural plate formation follow the principle of development:  often the signals promoting the specification of one cell type also block the specification of an alternative cell type.

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#Unit 4. Cell Communication and Cell Signaling

Anoikis 

Excess cells may also be extruded from epithelial layers, by a mechanically regulated process that can cause detachment and the loss of trophic survival signals

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#Id: 10500

#Unit 4. Cell Communication and Cell Signaling

Genes involved in controlling cell death encode proteins: 1. Killer or initiation proteins 

1. Killer or initiation proteins 

2. Destruction proteins 

3. Engulfment proteins

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#Unit 4. Cell Communication and Cell Signaling

Engulfment involves the assembly of a halo of actin in the engulfing cell around the dying cell, triggered by activation of Rac.

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#Id: 10502

#Unit 4. Cell Communication and Cell Signaling

Four genes play an essential role in controlling apoptosis during C. elegans development: 

ced-3, ced-4, ced-9, and egl-1

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#Id: 10503

#Unit 4. Cell Communication and Cell Signaling

In C. elegans BH3-only protein EGL-1 initiate apoptosis by binding to and inactivating CED-9

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#Id: 10504

#Unit 4. Cell Communication and Cell Signaling

Human Bcl-2 protein = C. elegans CED-9 protein

(23% identical in aa sequence)