Itga6 expression levels can drift in mouse BLCA cells, and are inversely correlated with their tumor‐generation capacity in mouse BLCA allograft/xenograft models.[11] The Tm4sf1+ TPCS in cancer were naturally segregated into two populations with low and high Itga6/Cd49f expression by unsupervised clustering, suggesting phenotypic heterogeneity in this population (Figure S11B,D, Supporting Information). Here, TM4SF1 is linked to bladder transitional cell carcinoma.