Malignant tumors are classified by their embryonic

tissue of origin:

Carcinomas -derive from epithelia such as endoderm

(gut epithelium) or ectoderm (skin and neural epithelia) 

Sarcomas - derive from mesoderm (muscle, blood, and

connective tissue precursors)

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#Unit 6. System Physiology – Plant

Second but distinct MYB-related protein, late elongated hypocotyl (LHY), has also been identified as a potential clock gene.

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#Unit 6. System Physiology – Plant

When the CCA1 gene is mutated so that no functional protein is produced, circadian and phytochrome regulation of four genes, including LHCB, is affected.

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#Unit 6. System Physiology – Plant

A protein kinase (CK2)CKB3 can interact with and phosphorylate CCA1, which is a multisubunit protein with serine/threonine kinase activity.

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#Unit 6. System Physiology – Plant

Phytochrome interacting factors (PIFs) act as negative regulators of photomorphogenesis.

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#Unit 6. System Physiology – Plant

PIFs promote etiolated development in the dark (skotomorphogenesis) primarily by serving as transcriptional activators of dark induced genes.

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#Unit 6. System Physiology – Plant

PIFs as constitutive transcriptional activators in the dark