[Solved] Extracting all characters from a string

I want to extract the string TC from the string TC10, the string can have any characters
out of [ATGC].

I used the following code but didnt get the right output. Please guide

nuc=match(val,/[ATGC]*/)
seq=substr(val,RSTART,RLENGTH)

---------- Post updated at 09:40 PM ---------- Previous update was at 09:31 PM ----------

sorry, this is solved... it had lowercase characters also :-/

nuc=match(val,/[ATGCatgc]*/)