Introns vs Exons

[kween]

According to Kaplan and firecracker,
"Splicing removes intron (introns go out of nucleus) and exons are rejoined (and expressed).

According to first aid,
"Introns stay in nucleus, and exons exit and are expressed"

Which is correct. Do we have to know which exits and which stays or is it just enough to know that exons are expressed?

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[Donald Juan]

Exons make up the final mRNA and definitely leave the nucleus for translation. Introns are most often degraded within the nucleus; although there is some evidence that some play roles in other things and may leave the nucleus--I'm almost 100% certain that is not board relevant. Just know that exons are expressed (i.e. go through mRNA processing and leave the nucleus for translation).