GBM12 brain cancer cells, a PDX model isolated approximately a decade ago, express all ERBB receptors, including a full-length mutated active ERBB1, and, as we observed with the mammary SUM149 cells, the enhancement of ruxolitinib toxicity in GBM12 cells required combined knock down of ERBB1, ERBB3, and ERBB4 (data not shown). The gene discussed is ERBB4; the disease is brain cancer.