Higher cell proliferation indices determined by Ki67 staining (22.5 ± 10.2 vs. 5.6 ± 4.6) were compensated by higher cell death rates as determined by TUNEL staining (1.1 ± 0.9 vs. 0.4 ± 0.4) in Brafthyr-V600E;Ptenthyr-Δ/+ mice as compared with Brafthyr-V600E mice (Fig 7), which likely explains the non-significant difference in tumor sizes between the 2 mouse groups (Fig 2). Here, MKI67 is linked to neoplasm.