Image showing two mice with engrafted tumors. OX40 in the tumor injected with CpG ODN exhibits an increase in the amount of the receptor OX40 (orange) in the injected tumor only. OX40 is also present in other organs of the immune system in both mice. Credit: Sagiv_Barfi, et al. Sci Transl. Med. 10, eaan4488 (2018).