Mer expression in t(1;19)-positive pediatric BCP-ALL patients was compared with t(1;19)-negative control ALL patients subdivided according to their CNS status at initial diagnosis and if they suffered from CNS relapse. CNS⁻/CNS⁺ BCP-ALL: BCP-ALL initially CNS negative or CNS positive, respectively. CNS⁻/CNS⁺ T-ALL: T-ALL, initially CNS negative or CNS positive, respectively. CNS⁻ BCP-ALL/T-ALL, CNS relapse: BCP-ALL or T-ALL, respectively, initially CNS negative, but CNS relapse later on. Remission BM: Mononuclear cells from t(1;19) BCP-ALL patients at remission (MRD negative). (A) Correlation analysis of Mer mRNA expression as determined by qRT-PCR and Mer protein expression as determined by FACS analysis in 45 t(1;19)-positive samples. (B) Mer expression (qPCR). Mer mRNA expression in the patient cohort measured by qRT-PCR. (C) Mer expression (FACS). Mer protein expression in the patient cohort measured by FACS. The 697 and MHH-CALL3 cell lines were included as controls.