JAK2 and neoplasm: Interestingly, a recent study showed that GM‐CSF secreted from tumor cells could promote PD‐L1 expression in liver myeloid‐derived suppressor cells through Janus‐activated kinase 2 (JAK2)‐mediated activation of signal transducer and activator of transcription 3 (STAT3), which was able to bind to PD‐L1 promoter and enhance its transcription (Thorn et al., 2016).