VBA Code - Color Changing Cells

I am trying to create a model that has a mixture of conditional formatting and data validation formulas within it, but have run into a problem in one area. Essentially, cell E10 is a Validation which pulls a drop down list of names. One of the options in this list is "Other".

I want to create a VBA code to make sure that cell E12 will get rid of any input, turn grey (color index = 15), and potentially lock (if possible!) if the "Other" is chosen by the user in cell E10. If any other value is chosen for cell E10, Cell E12 needs to remain unlocked and white (color index=2).