Catalyzes the NADPH-dependent reduction of ketopantoate into pantoic acid. (R)-pantoate + NADP(+) = 2-dehydropantoate + H(+) + NADPH Cofactor biosynthesis; (R)-pantothenate biosynthesis; (R)-pantoate from 3-methyl-2-oxobutanoate: step 2/2. Was identified as a high-confidence drug target. Belongs to the ketopantoate reductase family. Truncated N-terminus.