MAPK1 and neoplasm: In human lung cancer samples, a negative correlation was observed between CD55/59 and CD8+ T cell infiltration, and anti‐CD55/CD59 and anti‐PD‐1 showed synergistic tumor‐inhibiting effects.[337] EGFR‐activating mutations can also increase the expression of B7‐H4 (another novel immune checkpoint) through the MEK/ERK pathway and downregulate PD‐L1 via PI3K/Akt.