*2.2. MAP1B Immunoexpression and Clinicopathological and Genomic Correlations in UTUC and UBUC*

The association of clinicopathological characteristics with *MAP1B* immunoreactivity is shown in Table 2. We found, in UTUC cases, that high *MAP1B* expression was markedly associated with synchronous multiple tumors (*p* = 0.024), advanced pT status (*p* = 0.005) (Figure 2A–C), positive lymph node metastasis (*p* = 0.002), the presence of vascular invasion (*p* < 0.001), and an increased mitotic rate (*p* < 0.001) (Table 2 and Figure 2D). Similarly, in cases with UBUC, we found evidence of associations between increased *MAP1B* expression and advanced pathological tumor stage (*p* < 0.001), positive lymph node metastasis (*p* = 0.012), a high histological tumor grade (*p* = 0.016), the presence of vascular invasion (*p* = 0.045), and an increased mitotic rate (*p* = 0.006) (Table 2 and Figure 2E). Of note, none of the 30 cases displaying high *MAP1B* expression enrolled for mutational analysis were positive for *MAP1B* mutation, suggesting a mutation-independent expression of *MAP1B*.

**Figure 2.** Representative sections of *MAP1B* immunostaining. Note the stepwise increments in *MAP1B* immunoreactivity from the nontumoral urothelial epithelium (inlet) and (**A**) noninvasive papillary UCs to (**B**) non–muscle-invasive (pT1), and (**C**) muscle-invasive (pT2–pT4) UCs. A comparison of mitotic activity showed significantly higher mitotic rates in (**D**) UTUC and (**E**) UBUC cells with increased *MAP1B* expression than in cells with low expression.



*Cancers* **2020** , *12*, 630
