hMSCs contaminated with HeLa cells were fixed with 4% paraformaldehyde
in PBS (Nacalai Tesque) for 10 min at room temperature
(RT) and blocked in Blocking One (Nacalai Tesque) for
30 min at RT. The cells, then, were incubated with anti-HPV18 E7
antibody (8E2) (abcam) diluted at 1:500 in the blocking solution
(PBS containing 5% Blocking One) for 1 h at RT for primary staining,
and secondarily stained with goat anti-mouse IgG Alexa Fluor 488
(1:1000; Invitrogen) in the blocking solution for 45 min at RT. The
cells were mounted with VECTASGIELD mounting medium with
DAPI (VECTOR) and observed with a fluorescence microscope (