Muscle cells have an abundant, modified smooth ER called the sarcoplasmic reticulum.

The release and reuptake of Ca2+ by the sarcoplasmic reticulum trigger myofibril contraction and relaxation, respectively

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#Unit 4. Cell Communication and Cell Signaling

Intrinsic apoptosis pathway

Caspase-8 cleaves the BH3-interacting-domain death agonist (Bid), resulting tBid fragment

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#Unit 4. Cell Communication and Cell Signaling

TLS Online TPP Program

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#Unit 4. Cell Communication and Cell Signaling

tBid fragment binds to Bcl-2 on the outer mitochondrial membrane, leading to the dissociation of Bak and Bax and release of cytochrome c into the cytosol

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#Unit 4. Cell Communication and Cell Signaling

In cells lacking functional caspase-8 or FADD, TNFα

triggers an alternative pathway, necroptosis.

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#Unit 4. Cell Communication and Cell Signaling

TLS Online TPP Program

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#Unit 4. Cell Communication and Cell Signaling

Necroptosis pathway triggered by activation of RIPK1 kinase.