Table 2.

Expression of Components of RA Metabolism in NE-4C and RGl Neural Stem Cells

					RGl cells
		NE-4C cells			nondifferentiated		differentiated
		nondifferentiated	differentiated		EGF+		EGF−
Function	mRNA	serum +	serum withdrawal	retinoic acid	e	a	e	a
Uptake and storage	Rbp4	+	+	+	+	+	+	+
	Stra6	+	↑	↑	−	−	↓	↑
	Lrat	+	+	↓	−	−	↓	↑
RA synthesis	Rdh10	+	↑	↑	+	+	+	+
	Raldh1	−	↑	↑	+	+	↓	↑
	Raldh2	−	↓ ↑	↑	−	−	↓	↑
	Raldh3	+	↓ ↑	↑	+	+	↓	↓
	Raldh4	+	+	+	−	−	−	−
Intracellular transport	CrbpI	+	+	↑	+	+	↓	+
	CrabpI	−	−	↑	+	+/−	+	+/−
	CrabpII	+	+	↑	+	+	+	+
RA catabolism	Cyp26a1	−	↑	↑	−	−	−	↑
	Cyp26b1	+	+	↑	−	−	+/−	−
	Cyp26c1	−	−	↑	−	−	−	−
RA receptors	Rarα	+	+	+	+	+	+	+
	Rarβ	−	↑	↑	+	+	+	+
	Rarγ	+	+	+	+	+	+	+
	Rxrα	+	+	+	+	+	+	+
	Rxrβ	+	+	+	+	+	+	+
	Rxrγ	+	+	+	−	−	−	−

“+” and “−” indicate the presence or absence of the transcripts; the arrows indicate up- or downregulation of gene expression upon differentiation, not specifying the magnitude of growth or decrease. The table summarizes the results of real time PCR and RT-PCR data obtained from several experimental series (see Materials and Methods), represented in Figs. 4–8.

e, embryonic; a, adult.