View the animation below, then complete the quiz to test your knowledge of the concept.

1		Growth factor receptors are typically found in the
			A)	cell membrane.
			B)	cytoplasm.
			C)	nucleus.
			D)	mitochondria.
			E)	Golgi apparatus.
2		The growth factor-receptor complex initiates
			A)	DNA replication.
			B)	mRNA transcription.
			C)	protein synthesis.
			D)	protein kinase cascades.
			E)	protein breakdown.
3		Proteins that stimulate cell division include
			A)	caspases.
			B)	cyclins.
			C)	cyclin-dependent kinases.
			D)	caspases and cyclins.
			E)	cyclins and cyclin-dependent kinases.
4		Animal cells divide usually only when specific growth factors are present.
			A)	True
			B)	False
5		There are only a few types of growth factors.
			A)	True
			B)	False