PECAM1 and neoplasm: Similar to the findings in a previous report (Mancuso et al., 2006), 7 days of regorafenib or axitinib therapy induced a marked decrease of CD31 density, but showed a marginal effect on α‐SMA+ perivascular cells (Figure 1b and c, and Figure S1b and c), which indicated that AA‐TKI therapies often led to residual perivascular cells in tumour tissues.