[BioC] Variance

[David martin]

Hello,
I'm newbie with R.
I have a dataframe as follows. The microarray data has been normalized 
using spike in controls and the values shown are normalized log2 values.

	CondA	CondB	CondC	CondD	CondE
geneA	-6.19	-5.74	-5.82	-5	-5.59
geneB	-6.33	-5.32	-5.6	-4.88	-5.39
geneC	-6.15	-6.07	-5.6	-4.88	-5.9
geneD	-6.57	-6.11	-6.36	-5.36	-5.96
geneD	-6.74	-6.2	-5.49	-5.35	-5.95
geneE	-6.75	-6.24	-5.73	-5.63	-6.02

 From this small subset (in fact i have a larger dataframe) i would like 
to know which gene has the lowest variance. I would like to see is some 
of these genes could be used as reference genes for RT-PCr experiments.
How can i plot and get the variance from this genes and see what would 
the best candidates to be used as reference genes.

thanks,

david