If you'll notice in panel five, that's Kleiner's pet headcrab, Lamarr, in the background. Oh wait, I forgot to put him in after trying to remember all day that I should put him in. Dang. Let's just say he's off munching on some melon in the other room.

By the way, I should point out that the door Frohman is walking into in panel three does actually lead to Kleiner's lab. It's the same area you later pass through when you're leaving the lab with Dog after getting back from Nova Prospekt (though it's more smashed up and crumbled then). I should also point out I didn't realize this until I was done posing the scene, and I said, "Huh. This actually is the right spot." I just picked it because, hey, I needed a door.