How can I effectively remove dried cat pee from a mattress?

To effectively remove dried cat urine from a mattress, you can try using a mixture of white vinegar and water to clean the affected area. First, blot up as much of the urine as possible with paper towels. Then, spray the vinegar solution onto the stain and let it sit for a few minutes before blotting it up with a clean cloth. Repeat this process until the stain and odor are gone. You can also sprinkle baking soda on the area after cleaning to help absorb any remaining odor.