In agreement with the results described previously for germline Wip1-knockout mice (Ppm1dtm1Lad/tm1Lad)27,28,47, Ppm1dFes-cre mice displayed reduced lymphocyte and increased granulocyte numbers in peripheral blood, with lymphopenia and neutrophilia progressing with age (Fig. 1a). This evidence concerns the gene PPM1D and lymphopenia.