Agree with the above. I considered putting off applying for a year to focus on research, although MCAT expiry wasn't a concern though (and I think that is enough motivation not to delay especially if you're happy with your score). I'm glad I didn't wait because my GPA/MCAT + proof of research experience (LORs, essays, interviews) were sufficient to propel me through the cycle successfully. Now I'm in a nice program and have 2 papers in the pipeline, and I realize if I'd waited to publish I would probably be in the same place, but one year behind.