using regular expressions

I am looking for some advice on using a regular expressions when converting books in Calibre


I want to search for a series of words and identify them if they start with a lowercase letter or if they start with an uppercase letter.


Four example

Changing 'cute' to 'sweet'
and changing 'Cute' to 'Sweet'

Is there a way to specify this as part of a regular expression without having to duplicate each search and replace entry?

Thanks