Fig 9. STAT3 is necessary for delayed differentiation and increased keratinocyte proliferation in a stratified epithelium.

A) Representative organotypic raft cultures of NHK and HPV18-containing keratinocytes transduced with empty lentivirus and lentivirus expressing a dominant negative phosphorylation null Y705F mutant STAT3 fixed at day 14 and stained with haematoxylin and eosin (H&E) to assess morphology. Sections were also stained with antibodies specific for B) cyclin B1 C) involucrin and D) E1^E4. Nuclei are visualised with DAPI (blue) and white dotted lines indicate the basal cell layer. E) The number of cells positive for cyclin B1 and E1^E4 in the empty vector and Y705F STAT3 transduced HPV18-containing keratinocyte sections was counted in 5 fields of vision from sections of three independent raft cultures from two donor lines. Bars represent means ± standard deviation. ***P<0.001 (Student’s t-test) compared to empty vector control.