Conversation so far:
What was the relation between Nas and mainstream direction?
Columbia Records began to press Nas to work towards more commercial topics, such as that of The Notorious B.I.G.
Which commercial topic did Nas work on?
It Was Written is a departure for Nas from the raw, underground tone of his debut album towards a more polished, mainstream sound.
What was the relationship between him and Notorious B.I.G.
Nas had featured on several of Notorious B.I.G.'s tracks.

Question: What was his contribution to the mainstream or the firm?
Self-contained rewrite: What was Nas' contribution to the mainstream or the firm?