[R] heatmap for gene clustering?

[Hyung Cho]

I am using "heatmap" to cluster genes in microarrays. It works fine with 
100~200 genes.
But when I draw a heatmap with 600 genes, I can't read a clustering tree 
well.
Maybe I will be able to read it by dividing it into several subtrees using a 
function such as "subtree".
I found "subtree" in Splus, but not in R. Is there a similar function in R?
Or, without it, how can I solve this problem?

HJ

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