If the person loses the job while I485 is pending for >180 days
(with an approved I140), then he/she technically becomes out of status after 10 days of losing the job.
INS wouldn't know the fact that the person lost the job, but if there
is any RFE on the way for employment verification (like paycheck or
letter of employment etc), then the person is in deep sh*t.
If the person feels that he/she is going to lose the job before getting I485
approval, then it's better to find a new job using AC21 portability rightaway
w/o wasting any time.