Can a DataGrid cell be refreshed with UpdateSource?

I have a DataGrid that suffers from delayed binding (it only binds properly when the user presses <Enter> and moves one row down, not with <Tab> which is horizontal). I thought that I had found a perfect solution here:

    UpdateSourceTrigger Property

But alas, the provided example is for a TextBox:

// itemNameTextBox is an instance of a TextBox
BindingExpression be = itemNameTextBox.GetBindingExpression(TextBox.TextProperty);
be.UpdateSource();

All I need is an expression to type to the left of UpdateSource(). Isn't the DataGrid cell a kind of TextBox? I am sure they share ancestors...

TIA