Expression of MafB in adult thymus cells and nude 3PPs. (A) Quantitative PCR analysis of MafB transcript levels in indicated cell fractions isolated from adult C57BL/6 mice. MafB mRNA levels were normalized to GAPDH mRNA levels and are indicated as the ratio to the amount expressed in CD45⁺ leukocytes. Means and standard errors of the results obtained from 4 independent measurements are shown. (B) Quantitative PCR analysis of MafB and PD-L1 transcript levels in microdissected 3PPs from E11.5 nu/+ mice or E11.5 nu/nu mice. mRNA levels were normalized to GAPDH mRNA levels and are indicated as the ratio to the amount expressed in nu/+ 3PPs. Means and standard errors of the results obtained from 3 independent measurements are shown. (C) In situ expression analysis of MafB in developing thymus by monitoring GFP expression (green) derived from the MafB⁻ allele, in which the coding sequence of MafB was replaced with GFP, of MafB^+/− heterozygous mice.³¹  Paraformaldehyde-fixed E15.5 thymus sections were stained with anti-pancytokeratin antibody (red). Scale bars indicate 100 μm. Representative results of 10 different sections are shown.