Although degradation selectivity cannot be addressed in SMARCA4mut models due to the deficiency in human SMARCA4, we were able to monitor murine SMARCA4 protein levels within the tumor microenvironment of HCC515 and HCC2302 xenografts (see Supplementary Fig. 5b for in situ confirmation of stromal SMARCA4 signal). Here, SMARCA4 is linked to neoplasm.