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. This evidence concerns the gene CD274 and AL amyloidosis.