The function of HSH2D (hematopoietic SH2 domain containing, Ensembl gene identifier ENSG00000196684) is as follows. May be a modulator of the apoptotic response through its ability to affect mitochondrial stability (By similarity). Adapter protein involved in tyrosine kinase and CD28 signaling. Seems to affect CD28-mediated activation of the RE/AP element of the interleukin-2 promoter. {ECO:0000250, ECO:0000269|PubMed:11700021, ECO:0000269|PubMed:12960172, ECO:0000269|PubMed:15284240}.