transcriptional attenuation

[Raegan]

why is there transcriptional attenuation in cells?
more specifically, why is there transcriptional attenuation in genes which are known to be oncogenic? for instance, if c-myc, is only required in a small amount, why was the gene made with so many fricken exons, and that transcriptional attenuation is needed to stop transcription after the first intron?
thanks.