H1B extension/transfer possible?

[pooreb3]

I am the applicant of AOS (Adjustment of Status). It was filed by Employer A in 2004. We filed for AOS in july 2007. I had H1 renewed until last year 2011. We had applied EAD alongwith AOS. In year 2010 I joined Company B. So I started working on EAD. This year we were late in applying for renewal. So EAD is expired and I can not continue working.

My question is can company B file H1 transfer / Extension as of today with AC21? Once I-129 filed alongwith AC21 can I start working again for company B that I was working on EAD?