Expression of AID mRNA in PCFCL and PCLBCL, leg type. Expression of AID mRNA was measured in triplicate using quantitative real-time PCR and normalized to the expression of the housekeeping gene small nuclear ribonucleoprotein particle U1A (U1A). Error bars indicate standard deviations. Case numbers correspond to cases presented in Tables 1-2. dotted lines indicate the average AID mRNA expression within the group of PCFCL and PCLBCL, leg type; – indicates no tumor cells stained; +/– indicates less than 10% of tumor cells stained; and ++ indicates more than 50% of tumor cells stained. LN indicates lymph nodes; IHC, immunohistochemical staining; and nd, not determined.