Additionally, ATRT cell lines showed a similar sensitivity to abemaciclib in colony formation assays as MCF7 cells (Additional file 1: Fig. S7D), an ER+ breast cancer line known to be highly susceptible to CDK4/6 inhibition [34], whereas other non-ATRT solid tumors showed substantially lower sensitivity to CDK4/6 inhibition. This evidence concerns the gene CDK4 and breast cancer.