The RNA transport factor PHAX is required for proper histone H2AX expression and DNA damage response

Suppression of H2AX expression by knockdown of PHAX. (A–C) U2OS cells were transfected with the indicated siRNAs, followed by treatment with ADR at 1 µg/mL. After 5-h incubation, the indicated protein levels were determined by western blotting analysis (A,B) and immunostaining analysis for PHAX and γH2AX (C). The intensities of protein bands were quantified (B). (D) U2OS cells were cotransfected with siPHAX and a PHAX-expressing plasmid, followed by UV-irradiation (20 J/m²). After 5-h incubation, cells were fixed and immunostained for PHAX and γH2AX. (E) U2OS cells were treated as in A or D. The indicated protein levels were similarly determined.