Abstract
This study reports the identification and partial characterization of a novel Mr 105,000 nucleolar antigen (P105) identified by a monoclonal antibody. This monoclonal antibody was obtained when a nucleolar protein extract separated from the immunodominant protein C23 was used as the immunogen. Nucleolar antigen P105 was not detected in normal (resting) human liver, kidney, or peripheral blood lymphocytes but was present in a variety of human malignant cells and tissues. Lymphocyte nucleoli also exhibited specific P105 staining after 72 h of phytohemagglutinin stimulation. Nucleolar antigen P105 was detected in growing and dividing HL 60 cells but was not detected in retinoic acid-induced differentiated HL 60 cells. When HeLa cells were made quiescent by 48 h of serum starvation, the P105 antigen was not detected, but after refeeding with serum-containing medium, the antigen P105 was detected in the HeLa nucleoli within 2 h. These results indicate that nucleolar antigen P105 is a proliferating cell nuclear and nucleolar antigen-like molecule which appears early in the G1-S phase of the cell cycle.
Footnotes
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↵1 These studies were supported by the Cancer Research Center Grant CA-10893, P1, awarded by the National Cancer Institute, Department of Health and Human Services, USPHS; The DeBakey Medical Foundation; the Davidson Fund; the Pauline Sterne Wolff Memorial Foundation; the H. Leland Kaplan Cancer Research Endowment; the Linda and Ronnie Finger Cancer Research Endowment Fund; the William S. Farish Fund; and the Sally Laird Hitchcock Fund.
- Received April 27, 1987.
- Revision received August 19, 1987.
- Accepted August 24, 1987.
- ©1987 American Association for Cancer Research.