An early study (Liu et al., 2007) in multiple myeloma cells showed that IFN‐γ promoted PD‐L1 expression through a MyD88‐, TRAF6‐ and MEK‐dependent pathway, and IFN‐γ activated transcription factor STAT1 partially via the MEK/ERK pathway. Here, MAPK1 is linked to AL amyloidosis.