Ear swelling during PMA treatment. Ear thickness of PMA-treated ears (■) and solvent-treated contralateral ears (▴) was monitored with a caliper over a period of 6 weeks. Means and SDs of 3 mice per genotype are shown. Data are representative for 1 of 2 complete and independent experiments. Mice used were 13 weeks (Kit+/+ [C57BL/6]), 8 weeks (KitW/Wv), 10 weeks (R−γ−), 16 weeks (R−γ−KitW/Wv), 2 × 9 weeks, and 1 × 16 weeks (KitW/W) old.