Rulebook (pg 13);
"Influence may be spent during the game in the following situations:
- A Player takes a Location Action during a Kicked-Out Action
- A Player takes the Promotion Action from Media Center
- A Player uses money to buy a Work of Art, hire Assistants or make an offer in the International Market
- A Player performs an action which increases the Fame of an Artist"
Thanks! That's a game changer in a few games I've played.