Fig. 2

ErbB3 loss decreases proliferation and cell survival of luminal, but not basal, MECs during pregnancy. Mammary glands harvested from 12–15-week-old mice at 16.5 d.p.c., L1, and L5. Representative images are shown. Original magnification is 400×. P values calculated using Student’s unpaired two-way t test. a IHC detection of Ki67. N = 9. Lower panel: percentage of MECs that were Ki67⁺. Each data point represents the average of two random 400× fields from a single tumor; midlines are average of samples within the group ± SD. b TUNEL analysis, N = 12. Each data point represents the average of two random 400× field from a single tumor; midlines are the average of samples within the group ± SD. c. IF staining of K5 (red) and K8 (green). Sections were counterstained with DAPI. Yellow arrows indicate basal location of K5⁺ cells; white arrows indicate apically localized K5⁺ cells. d Quantitation of the percentage of MECs that were K8-positive/K5-negative. N = 5. Each data point represents the average value of three random 400× fields per sample; midlines are the average of all biological replicates ± SD. dpc days post coitus, Lact d lactation day, TUNEL terminal dUTP nick end-labeling (Color figure online)