The Lions' defensive line starting four is set in cement with Kyle Vanden Bosch and Cliff Avril at the ends, while rookie Ndamukong Suh and Corey Williams clog up the middle.

But after that the situation gets murky.

DT Sammie Hill has shown great improvement over last year when he was a starter. He won’t see near the playing time as last season, but he’ll get his share of snaps.

DE Turk McBride has had a good camp too -- enough to impress defensive coordinator Gunther Cunningham.

DE Jared DeVries is a huge question mark. If he’s able to recover from his knee injury quickly, will he be in the mix? The 34-year-old DeVries missed all of last season with an Achilles injury, but worked during OTAs with no hindrance.

When the Lions traded for DE Lawrence Jackson last week, bringing him in from Seattle, there was some thought he might replace DeVries on the roster.

Can’t see that happening now. Jackson, who has a hamstring injury, has not practiced. He’s got a lot of catching up to do in a short period of time. The former first-round pick is now a huge question mark. I’m no body language expert, but Jackson doesn’t appear to be into it at practice.

The only other defensive ends on the roster are rookies who don’t appear ready to go. They are seventh-round pick Willie Young and undrafted free agents Chima Ihekwoaba, a Canadian, and Korey Bosworth, nephew of Brian Bosworth.

At defensive tackle, the Lions are looking for third-year defensive tackles Landon Cohen and Andre Fluellen to step up. They also have undrafted rookie Robert Callaway from Saginaw Valley State.

The Lions still have two preseason games to help them make their decisions, starting on Saturday when they meet Cleveland at 5 p.m. at Ford Field.

(Follow me on Twitter @paulapasche.)