To explore the relevant target(s) in CLL, we analyzed RNA expression data, which showed that BLK, GAK, IRAK1a, and MAPK9/14 are expressed in CLL; thus it is possible that the activity of afatinib in CLL is mediated via one or more of those components (Supplementary Fig. 18A). Here, GAK is linked to B-cell chronic lymphocytic leukemia.