To test this hypothesis, we treated several human breast cancer cell lines (MCF-7, T47D, MDA-MB-157, and MDA-MB-231) with IL-24 in the presence or absence of the specific PKA inhibitors, H-89, and PKI peptide (sequence: Myr-Gly-Arg-Thr-Gly-Arg-Arg-Asn-Ala-Ile-NH2). Here, IL24 is linked to breast cancer.