Filter letters and numbers using Knime

Hi,

I am new to Knime. Just wanted to ask for help on how I can filter a combination of letters and numbers using the Column Expressions node. Here is an example of the items I need to filter:

C1726UBB

C1778UBB

C4602UBC

C4603UBC

MST2036F

These items can start with any letter and may contain different combinations of letters and numbers.

Hope somebody can help me.

Thanks!