Working Excel97 SR2

I have a sheet with a number of comboboxes. When I enter a cell containing
a combobox I want to activate the combobox and do a
Combobox1.Dropdown

At present I am using event code for each cell but would like to write
generic code to identify the combobox in the cell. (I could use a secondary
column to contain the the combobox #)

Can anyone suggest code that could do something like
Comboboxx.Dropdown

Thanks in advance...
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sb