LARadio.com's Don Barrett has the skinny on the end of Mark & Brian, the duo that has been waking up KLOS-FM listeners since September 1987. Don's site is password-protected, so here's a summary from Radio-Info:
Hard to believe it’s been 27 years since WAPI, Birmingham PD Mark St. John connected DJ Thompson and improv comedian Brian Phelps, and coming up on 25 years since they invaded rock KLOS, Los Angeles in September 1987. They’ve had a TV show, won a Marconi, been syndicated on the west coast, and gotten a star on the Hollywood Walk of Fame. But a couple of years ago (according to Don Barrett’s LARadio.com), Thompson’s wife noted that she’d been cancer-free for a number of years and that “all those things we’ve talked about that we want to do…I want to do them.” Long story short, they’re happily living on Lake Norman, outside Charlotte, when Mark’s not staying at L’Ermitage Hotel, near the KLOS studios. His last “Mark and Brian Show” will be August 17. What happens then? Thompson tells Don Barrett that Phelps would like to continue in mornings at the Cumulus classic rocker, and says "they are interested in keeping him and [are] moving toward doing that."
You may also remember Mark & Brian hosted an ill-fated TV show on NBC: