Where, though, do these hereditary variations come from?

This was the great gap in Darwin’s theory, and he never filled it. The problem was serious because, according to the prevailing belief in blending inheritance, variation should decrease, not increase.

TLS Online TPP Program

#Id: 10423

#Unit 4. Cell Communication and Cell Signaling

Tumor cells secrete a protein plasminogen activator that converts the serum protein plasminogen to the active protease plasmin.

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#Id: 10424

#Unit 4. Cell Communication and Cell Signaling

Noncoding RNAs, especially microRNAs, play a critical role in tumorigenesis:

Let-7 miRNAs

miR-15-a 

miR-16-1

miR-21

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#Id: 10425

#Unit 4. Cell Communication and Cell Signaling

Let-7 miRNAs repress the translation of Ras mRNA and also targets MYC

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#Id: 10426

#Unit 4. Cell Communication and Cell Signaling

miR-15-a and miR-16-1, control the proliferation of 

B cells

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#Id: 10427

#Unit 4. Cell Communication and Cell Signaling

miR-21 targets PTEN phosphatase

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#Id: 10428

#Unit 4. Cell Communication and Cell Signaling

DNA methylation occurs at cytosines of CpG islands, leads to repression of the promoters. DNA hypermethylation & DNA hypomethylation is also a hallmark of cancer.