Quickly heals several of his ribs

Cell blocked the Ultra Super Saiyan's first punch with relative ease. At least, bringing his arm into position for a block was easy. But the force shattered all his expectations; the single blow smashed straight past his attempted block and crashed into his chest. Pain shot through his torso as he was hurtled to the ground, cratering on the smoldering ground with a THUD that shook the entire island.

'Shit!' thought Cell as he rolled over, pushing himself to his feet. The single blow had cracked several of his ribs; he took a few deep breaths before his regeneration began knitting them together again.

- Bringer of Death Chapter 52