Stains & CD markers
MDR / CD243

Last author update: 1 April 2010
Last staff update: 2 July 2021

Copyright: 2002-2023,, Inc.

PubMed Search: CD243

Nat Pernick, M.D.
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Cite this page: Hamilton K, Pernick N. MDR / CD243. website. Accessed June 10th, 2023.
Definition / general
  • "Detoxifying agent" that pumps toxins / drugs out of cells
  • Also transports steroid hormones and transports substances across blood-brain barrier
  • Also mediates the ATP driven efflux of drugs from multidrug resistant cancer and HIV infected cells
  • P glycoprotein is product of MDR1 gene
  • Also called MDR1 gene (multidrug resistance to cancer), P glycoprotein 170 (molecular weight is 170K), ABCB1, P-binding cassette subfamily B member 1
  • Antibody C219 binds to both ATP binding regions of P-glycoprotein and inhibits its ATPase activity and drug binding capacity
  • Widely used as a tumor marker but cross reacts with HER2 / CerbB2 (Proc Natl Acad Sci USA 1999;96:13679)
  • Antibody C494 detects an internal cellular epitope present only on the Mdr1 isoform of P-glycoprotein with strong plasma membrane staining patterns
    • It cross reacts with pyruvate carboxylase, an abundant mitochondrial enzyme (weak, homogeneous, cytoplasmic or granular patterns) but unlike C219, it does not cross react with Mdr3
  • Antibody JSB1 appears to have similar behavior as C494, as it cross reacts with pyruvate carboxlyase (J Histochem Cytochem 1995;43:1187)
Clinical features
Uses by pathologists
Microscopic (histologic) images

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Normal tissue:
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Duodenum, fig C, D

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Lung, fig 1A

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Lung, figs D, E

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Retinal pigment epithelium

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Hepatocellular carcinoma, globular intracytoplasmic stain

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Renal cell carcinoma

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Retinoblastoma, figs 1, 2

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Positive staining - normal
Positive staining - disease
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