ASP.NET: Question about the column-line-wrapping feature in gridviews

Question

I have a ASP.NET gridview (embedded in a DIV) with several columns. For some columns line wraps are definied and for some not(with ItemStyle.Wrap = true/false). For all columns ItemStyle.Width is set to a specific value. Now I am wondering, that there is a line wrap in a column, where ItemStyle.Wrap = false. What could be the reason for that?