if (/\bAPI|APIN|UWI\s*\./) { $myvar = $something; }

##</code><code>##

if (/\bAPI|APIN|UWI\s*\./) { somesub($matchedpart); }

##</code><code>##

if (/\bAPI|APIN|UWI\s*./) {
     $matchedpart =~ /\bAPI|APIN|UWI\s*./;
     somesub($matchedpart);
}