Subject: What is the mechanism of Sister Chromatid Exchange ?

As we see that many anti-cancer drugs such as cyclophospamide, mitomycin 
C, cisplatin etc are genotoxic. they damage the DNA thereby killing the 
tumour tissues. To determine the genotoxicity of these drugs, one of the 
method is by using Sister Chromatid Exchange(SCE) as the end point.  
What is the mechanism of SCE & How do we relate SCE and Genotoxicity ?
                                       Thank you.

Re: What is the mechanism of Sister Chromatid Exchange ?