PGR and neoplasm: In support of this, Δ40p53 co-localised with a plasma cell marker (CD38) [26] in formalin-fixed paraffin-embedded (FFPE) slides of three ER (oestrogen receptor)+/PR (progesterone receptor)+/Her2 (human epidermal growth factor receptor 2)- IDCs (Supplementary Fig. 1), suggesting that this isoform is expressed in immune cells within the tumour microenvironment.