PIK3CD and infection: Finally, the mechanistic differences between Itpkb, PTEN, and Notch regulation of β-selection, and the aforementioned death due to hematopoietic failure or infections (26, 47) might explain why Itpkb−/− mice do not present the leukemias/lymphomas caused by excessive signaling of Notch, PI3K, or Akt in DN3 cells (6, 95, 98).