CD44

The CD44 protein is a cell-surface glycoprotein involved in cell-cell interactions, cell adhesion and migration. CD44 is also known as Homing-cell adhesion molecule (H-CAM) and Phagocytic glycoprotein-1 (PgP-1). A specialized sialofucosylated glycoform of CD44 called HCELL is found natively on human hematopoietic stem cells and functions as a “bone-homing receptor”, directing migration of human hematopoietic stem cells and mesenchymal stem cells to bone marrow.

This protein participates in a wide variety of cellular functions including lymphocyte activation, recirculation and homing, hematopoiesis, and tumor metastasis. Transcripts for this gene undergo complex alternative splicing that results in many functionally distinct isoforms; however, the full-length nature of some of these variants has not been determined. Splice variants of CD44 on Colon Cancer cells display the HCELL glycoform, which mediates binding to vascular E-selectin under hemodynamic flow conditions, a critical step in Colon Cancer metastasis. In addition, variations in CD44 are reported as cell surface markers for some breast and prostate cancer stem cells and have been seen as an indicator of increased survival time in Epithelial Ovarian Cancer patients.

CD44 is a mouse monoclonal antibody derived from cell culture supernatant that is concentrated, dialyzed, filter sterilized and diluted in buffer pH 7.5, containing BSA and sodium azide as a preservative.

1. Li et al. Cell Research. 2007;17:3-14
2. Sillanpää S, et al. Clin Cancer Res. 2003;9(14):5318-24
3. Yasuda M, et al. Histol. Histopathol. 2003;17(3): 945-50
4. Ponta H, et al. Nat. Rev. Mol. Cell Biol. 2003;4(1): 33-45

1. Cut and mount 3-4 micron formalin-fixed paraffin-embedded tissues on positive charged slides.
2. Air dry for 2 hours at 58° C.
3. Deparaffinize, dehydrate and rehydrate tissues.
4. Subject tissues to heat epitope retrieval using a suitable retrieval solution such as ImmunoDNA Retriever with Citrate (BSB 0020-BSB 0023) or EDTA (BSB 0030-BSB 0033).
5. Any of three heating methods may be used:
   • Electric Pressure Cooker
     Place standoff rack at base of pressure cooker. Add 1-2 inches of distilled water to the pressure cooker and turn heat to high, and incubate for 15 minutes. Open and immediately transfer slides to room temperature.
   • Water Bath Method
     Place tissues/slides in a pre-warmed staining dish or coplin jar containing the ImmunoDNA Retriever with Citrate or EDTA in a water bath set at 95°-99° C. Incubate for 30-60 minutes.
   • Conventional Steamer Method
     Place tissues/slides in a pre-warmed staining dish or coplin jar containing the ImmunoDNA Retriever with Citrate or EDTA in a Steamer, cover and steam for 30-60 minutes.
6. After heat treatment, transfer slides in ImmunoDNA Retriever with Citrate or EDTA to room temperature and let stand for 15-20 minutes.
7. Wash slides with IHC wash buffer or DI water.
8. Continue IHC staining protocol.