Fill in the response. DIALOG:
[a]. what are the different steps of dna damage
[b]. ALC1 relaxes chromatin at sites of UV damage to DNA.
[a]. what else is important for the damage to occur
[b]. In addition, the ubiquitin E3 ligase complex DDB1-CUL4A carries out ubiquitination of the core histones H2A, H3, and H4, as well as the repair protein XPC, which has been attracted to the site of the DNA damage.
[a]. are there any other steps
[b]. XPC, upon ubiquitination, is activated and initiates the nucleotide excision repair pathway.
[a]. what else is known about the damage
[b]. Somewhat later, at 30 minutes after UV damage, the INO80 chromatin remodeling complex is recruited to the site of the DNA damage, and this coincides with the binding of further nucleotide excision repair proteins, including ERCC1.
[a]. how about transfections
[b]. Double-strand breaks (DSBs) at specific sites can be induced by transfecting cells with a plasmid encoding I-SceI endonuclease (a homing endonuclease).
[a]. what other methods are used
[b]. 
Multiple DSBs can be induced by irradiating sensitized cells (labeled with 5'-bromo-2'-deoxyuridine and with Hoechst dye) with 780 nm light.