Concatenated cell to dropdown

[TheDataCleaner]

Is it possible to convert a cell with concatenated names (John,Peter,Mike,Philip) into a dropdown list:

John
Peter
Mike
Philip

Thanks for helping out!

Gr. Sander

 

[GlennUK]

I think you have to convert it into a list of cells first, before you can use it in a Data Validation in-cell drop-down list. Is that kind of solution acceptable?