Is it posssible using shRNA vector to generate microRNA? - (Feb/07/2012 )

I would like to generate over-expression system with lentivirus. Can I use shRNA lentiviral vector? The shRNA use pol III such as U6 or H1, the CMV is better due to the pol ll. But, several paper revealed the pol lll also involved in the transcription of microRNA. Dose anyone think about that??

it should be possible with a pol II.

I'm not sure I understand the exact question, it is phrased a bit fuzzy. You can use pol III promoters for pre-miRNA expression and you can use pol II promoters to express pre-miRNA.
Just make sure the specific pol III terminators are no included in the pre-miRNA sequence.
And I'm not aware that there are endogenous examples of pol III driving a pre-miRNA, papers claiming so have been (to my knowledge) refuted.