Most importantly, however, the mice adoptively transferred with PD-1-/- pulmonary ILC2s had the least number of B16 tumor colonies at day 14, indicating that PD-1 inhibits important aspects of anti-tumor ILC2 response in vivo. Interestingly, total number of pulmonary ILC2s was not significantly different between the adoptively transferred groups (Supplementary 1B), indicating the decrease in tumor burden was independent of a difference in ILC2 number. Here, PDCD1 is linked to neoplasm.