[Isoform 1]: ATP-dependent transporter of the ATP-binding cassette (ABC) family that actively extrudes physiological compounds, and xenobiotics from cells. Mediates ATP-dependent transport of glutathione conjugates such as leukotriene-c4 (LTC4) and N- ethylmaleimide S-glutathione (NEM-GS) (in vitro), and an anionic cyclopentapeptide endothelin antagonist, BQ-123 (PubMed:11880368, PubMed:12414644). May contribute to regulate the transport of organic compounds in testes across the blood-testis-barrier (Probable). Does not appear to actively transport drugs outside the cell. Confers low levels of cellular resistance to etoposide, teniposide, anthracyclines and cisplatin (PubMed:12414644). {ECO:0000269|PubMed:11880368, ECO:0000269|PubMed:12414644, ECO:0000305|PubMed:35307651}. [Isoform 1]: Mediates the release of nucleoside triphosphates, predominantly ATP, into the circulation, where it is rapidly converted into AMP and the mineralization inhibitor inorganic pyrophosphate (PPi) by the ecto-enzyme ectonucleotide pyrophosphatase phosphodiesterase 1 (ENPP1), therefore playing a role in PPi homeostasis. {ECO:0000269|PubMed:24277820, ECO:0000269|PubMed:24969777}. [Isoform 2]: Inhibits TNF-mediated apoptosis through blocking one or more caspases. . This is the function of Ensembl gene identifier ENSG00000091262 (ABCC6, ATP binding cassette subfamily C member 6).