CD44isapolymorphicglycoproteinwhichparticipatesinawidevarietyofcell-cellorcell-matrixinteractionsincludinglymphocytehoming,establishmentofBandTcellimmuneresponses,tumormetastasisformationandinflammation.
ThreeisoformcategoriesoftheCD44moleculehavebeenidentified:
1)apredominant80-90kDacategory,theso-calledstandardformnamedCD44std,
2)anintermediatesizecategoryof110-160kDaand
3)acategorywhichincludesverylargeisoformsof250kDacovalentlymodifiedbytheadditionofchondroitinsulfate.

ThisCD44-familyoftransmembranereceptormoleculesisderivedfromasinglegenelocatedonchromosome11.AlternativesplicingofthemRNAgivesrisetothedifferentisoforms,containinginsertsofvaryingsizesintheextracellulardomainofthemolecule(exonsv2-v10).IncontrasttostandardCD44(CD44std)whichisalmostubiquitouslyexpressed,thevarietyofCD44isoforms(CD44var)haveamuchmorerestricteddistribution,e.g.,onkeratinocytes(exonsv3-v10),epithelialcells(exonsv(-v10),activatedlymphocytesandmacrophages(exonv6).
AsplicevariantofCD44(exonsv4-v7)confersmetastaticbehaviorinaratcarcinomamodel;aberrantexpressionofsplicevariantshasbeendetectedonavarietyofhumantumorcelllinesaswellasprimaryandmetastatichumantumors,includinglymphomas,carcinomas(colon,thyroid,mamma,bladder),andgliomas.
DetectionofabnormalregulationofCD44splicingthuscouldbehelpfulincancerdiagnosisanddiseaseevaluation.
ThesCD44var(v5)ELISAdetectsallcirculatingCD44isoformscomprisingthesCD44var(v5)sequences.DeterminationofsCD44var(v5)willprovidemoredetailedinsightintodifferentpathologicalmodificationsduringcancerandotherdiseases.

Synonyms:VFF-8PhagocyticglycoproteinI,Hermesantigen