How do i get teh checked state a DataGridViewCheckBox cell?

hi friends,

I have a datagridview with four columns and the last column is a checkbox column. I want to change the background color of the checkboxcell if it's checked. I used the event CellContentClick() to get the rowindex and columindex of that checkboxcell, but I cannot get it's checked/uncheck state?

thanks

I use Visual studio 2012 Ultimate and SQL server 2008 developer edition!