Conversation so far:
Where did the band form?
Chicago.
Did they play at any Chicago clubs?
Polish bar Chicago 21.
Were they popular in Chicago?
CANNOTANSWER.
What was their big break?
CANNOTANSWER.
Who was in the band during this period?
guitarist James Iha.

Question: Who else?
Self-contained rewrite: Who else was part of The Smashing Pumpkins band other than James Iha?