Impact of ionizing radiation on the miRNA biogenesis pathway. The radiation-response of AGO2 and DICER, that are involved in the late steps of the miRNA processing pathway, was assessed at the mRNA and protein levels. AGO2 and DICER1 mRNA expression 3 h after 6-Gy irradiation in proliferating (A) and differentiated keratinocytes (B) addressed by RT-QPCR (n=3; error bars represent SD; bilateral paired t-test : *p≤0.05, ***p≤0.001, NS: Non-significant). AGO2 and DICER1 protein level 3 h after 6-Gy irradiation in proliferating (C) and differentiated keratinocytes (D) addressed by immunoblotting. ACTB (Actin B) was used as loading control. (E) The expression of the primiR-191, primiR-200b and primiR-331 was assessed by quantitative qRT-PCR in proliferating keratinocytes 3 hours after 6 Gy-irradiation. Values are mean fold changes +/− SD of independent experiments performed in triplicate on keratinocytes from 3 different donors (bilateral paired t-test: *p≤0.05).