B16 mouse melanomas do not recapitulate common genetic mutations in human disease and are resistant to immunotherapies.27 The most frequent melanoma driver mutations are oncogenic BRAFV600E and loss of CDKN2A which are recapitulated in 2891L melanoma cells from Tyr-CreERT2; Rosa26-lsl-rtTA; tetO-BrafV600E; Cdkn2-/-; Pten-/- iBIP2 mice,28 and in YUMM3.3 cells from BrafV600E/+; Cdkn2a-/- mouse melanoma.29 RT-qPCR and Western blot analyses revealed that both cell lines transcribe endogenous Inhba and accumulate Activin-A protein in the supernatant (SN) (online supplemental figure S4A, B). The gene discussed is INHBA; the disease is melanoma.