Cara Heiden of Wells Fargo popped a list of 2006’s top 25 mortgage lenders on a lecture-hall screen at Iowa State University on Tuesday. All but eight were highlighted in yellow. They’re the companies on the list that remain in the wake of the 2007 credit crisis, said Heiden, co-president of Wells Fargo Home Mortgage, of West Des Moines. “Wells Fargo is still here because we’ve always led with responsible lending,” Heiden told lenders, students and others attending the Robert Stafford Lecture Series on Banking. “The key is to ensure the borrower has the ability to repay. It’s not rocket science. Unfortunately, some lost sight of that.”