Subsequently, the population of RASGAP deficient CRC organoids were intermittently cultured in the absence of EGF signaling activity (EGF depleted growth medium containing afatinib, a small molecule inhibitor that targets the tyrosine kinase receptors EGFR, HER2 and HER4) (Figure 2B). The gene discussed is ERBB4; the disease is colorectal carcinoma.