Figure 1. SB mutagenesis drives drug resistance in A375 through known and novel mechanisms.

(A) A375 SB100x+ cells were transfected with the pT2-Onc3 transposon before undergoing drug treat with either vemurafenib (5 µm; n=75), vemurafenib plus cobimetinib (5 µm and 5 nm respectively; n=20), or DMSO control (n=15). (B) The T2-Onc3 transposon can cause gain-of-function or loss-of-function mutations based on orientation of the transposon and location of insertion in the gene locus. (C) SB mutagenesis significantly increases the frequency of drug-resistant colonies in A375 cells following long-term exposure to vemurafenib or vemurafenib plus cobimetinib. (D) Drug resistance drivers were identified by profiling sites of transposon insertion in resistant cells to find genes that were recurrently over-expressed by transposon insertions.