An early locked position in a Scrabble game

In a Scrabble game, towards the end of the game the board can get locked, i.e. no player can play any more words no matter how many times they exchange their tiles. I tried to come up with a locked postion early in the game, and I came up with a solution with 9 tiles on the board. The following position's lockedness comes from these facts:

• No other word starts or ends with QIS 
• No other word starts with XU
• No other word starts with SOX (and only one other word ends with it: BOBBYSOX, and that doesn't help here)
• There are words that end with Q, but it is not possible to write them in this position since there is no 2 letter word that ends with Q

I'm referring to the TWL (Tournament Word List) here, since I play Scrabble mainly on Facebook. Also one Q and one X in the diagram are produced using the two blank tiles.

Please let me know if there is a solution with fewer tiles.

Here is the locked position: