We also routinely use Ki67, although have gotten some good qualitative 
results with PCNA. 
The different phases of the cell cycle are: G1 (growth and chromosome 
preparation), S (formation of centrosomes, synthesis of DNA - prophase, 
metaphase, anaphase and telophase), G2 (Preparation for mitosis), and  M 
(mitosis). G0(zero, not O), is when the cell "steps out" of the cell 
cycle and isn't actively proliferating.  This is why it would be 
misleading for purposes of analysis for the IHC to include these cells.
-Anne Lewin

Dana Settembre wrote:

>We use Ki67 and have rarely used PCNA.  What is "go"?   Is that a
>phase?
>Dana Settembre
>University Hospital - UDMNJ, Newark, NJ
>
>  
>
>>>>"Connolly, Brett M"  10/24/2005 5:44:40
>>>>        
>>>>
>PM >>>
>I have been a big proponent of using Ki67 instead of PCNA as a more
>accurate
>proliferation marker after reading that PCNA may in fact carry over
>into G0.
>Recently, some of my colleagues have been clamoring for PCNA.
>
>I'd be interested to hear which marker other labs are using.
>
>Thanks,
>Brett
>
>Brett M. Connolly, Ph.D.
>Merck & Co., Inc.
>MRL, Imaging Research
>WP-44K
>PO Box 4
>West Point, PA 19486
>PH 215-652-2501
>fax. 215-993-6803
>e-mail. brett_connolly@merck.com 
>
>
>
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