Figure 4.

Kif4A depletion renders cell hypersensitive to ionizing radiation. (A) Doxycycline (dox) was added into HeLa-tetK4Ai cell culture (see materials and methods) to induce Kif4A shRNA expression and then withdrawn 72 hours later to allow Kif4A expression recovery. Western blot showed Kif4A level changes during the course. (B) HeLa-tetK4Ai cells were exposed to Kif4A shRNA induced transiently for 48 or 72 hrs before the treatment of ionizing radiation and then replated for colony formation in doxycycline-free medium. Viable colonies were scored from triplicate experiments and the compiled survival curves were presented in logarithmic scale. Colonogenic survival assay was performed as described as previously.³²