E8 mutations do not influence differentiation or expression of cellular DNA replication proteins in organotypic cultures. Frozen sections of 12-day NHK, HPV16 wt (wt), HPV16 E8− (E8−), or HPV16 E8 KWK mt (E8 KWK mt) organotypic cultures were stained with antibodies against keratin 10 (K10), MCM2, MCM7, or PCNA and DAPI to detect cellular DNA.