EB1C and AC21 portability

[L1A_asp]

My company has filed for my GC in EB1C.We got the news that our client is not renewing the contract next year.
Incase i get fired and my i-140 has been approved and i485 filed, can i find a new employer and adjust using AC21?
I guess only challenge would be that i need to get my EAD before filing AC21.

[PS2015]

I think 180 days should be with current employer from 485 filing date also. Your new job should be similar to what mentioned in your 140 petition and new employer should agree to give you 485j supplement.