Ostensibly a warning about the perils of Hollywood-style self-absorption, Welcome Home Roscoe Jenkins feels too much like another one of those films in which movie-industry types admire the nobility of the rubes living in flyover country. Martin Lawrence plays the title character, who left his Georgia home behind, changed his name to Dr. R.J. Stevens and launched a hit daytime talk show in the Jerry Springer mode. The film begins with Daddy Jenkins (James Earl Jones) sternly suggesting that, after nine years in L.A., it’s time for Roscoe to come back for a family visit. The mayhem that ensues is largely driven by the clash between Roscoe’s uptight-vegan reality-TV-star wife (Joy Bryant) and family members like used-car salesman Clyde (Cedric the Entertainer) and boisterous, straight-talking, sweet-tea-guzzling Betty (Mo’Nique). Also on-hand is an old high-school crush, Lucinda (Nicole Ari Parker). The actors all try hard (Mike Epps as motormouthed cousin Reggie is a hyperactive standout) and there are a few laugh-out-loud gags — one of them involving a cheerfully explicit dog-on-dog sex scene — but talented writer/director Malcolm D. Lee (check out Undercover Brother) relies so much on hoary formula that his story and characters never come alive. It has its moments scattered here and there, but few surprises. C