HM during interview can find out whether the applicant lied in resume on one
or more of the requirements, and can then ask the applicant to provide
proof (his past experience letter from his past company, or from his
transcript, course pack,...). When the applicant does not comply, company
can legally drop this candidate for PERM purpose. Remember, USCIS also want
your proof (beyond what you wrote on your cv) that you meet all the job
requirements listed in the job descriptions.