DropDownList to DropDownList

I want to take the selected value of DropDownListA and based on that value do a query to the database and populate DropDownListB. For example, DropDownListA contains Entity values. If the user selects entity101 then I call stored procedure where I pass in the entity value, run a select statement and get a list of properties associated with the entity name. I want to take that list and populate DropDownListB. Easy enough to do with ASP.NET using the AutoPostBack. Would be real nice to do this with Atlas. Is it possible? If so, how?Atlas control toolkit has cascading dropdowns-please download the the controltoolkit and look at the sample application code for cascading dropdowns- that should help you,