Correlation between CD44 methylation and gene silencing. (A) Transcript levels of CD44 were analyzed by qRT-PCR in 40 lymphoma cell lines of the different lymphoma subtypes. RPS9 expression was used as endogenous control and cell line L-82 was used for normalization. CD44 was primarily expressed in HL and MCL cell lines. Note the strong correlation between CD44 methylation (green columns) and transcriptional silencing as well as CD44 non-methylation (yellow columns) and CD44 expression. The methylation status is shown according to MS-MLPA analysis. (B) CD44 protein expression was analyzed in the CD44 methylated and mRNA-negative cell line SC-1 (FL) and in the CD44 unmethylated, mRNA-positive cell line REC-1 (MCL) by flow cytometry. In accordance with mRNA expression, only cell line REC-1 was positive for CD44 protein. CD44 stained cells (filled histogram) and isotope control labeled cells (open histogram) are shown.