how to add a space using a regex

What I want to do is add a space between one's name when the are like the
following:

$name1 = "FirstLast:";

I want change $name1 = "First Last";

and

$name1 = "FirstMiddleLast:";

I want change $name1 = "First Middle Last";

To be able to add spaces for either "FirstLast:" or "FirstMiddleLast:" with
the same regex?

Thanks,

Jerry


.