Sum all columns with a wildcard name search using Python Pandas

I have a dataframe in python pandas with several columns taken from a CSV file.

For instance, data =:

Day P1S1 P1S2 P1S3 P2S1 P2S2 P2S3
1   1    2    2    3    1    2
2   2    2    3    5    4    2

And what I need is to get the sum of all columns which name starts with P1... something like P1* with a wildcard.

Something like the following which gives an error:

P1Sum = data["P1*"]

Is there any why to do this with pandas?