RB1 and sarcoma: The idea that RB1 is not the only target of the frequent deletions in this chromosomal region is reinforced by the fact that in the cohort of 106 sarcomas, 7% of tumors are deleted only for RB1, whereas 13% carry a deletion that only affects RCBTB1. Furthermore, in contrast to RCBTB1, RB1 is not associated with metastatic evolution in our cohort (Supplementary Figure S5).