KLRF1 and urinary bladder cancer: To determine if KLRF1 surface expression distinguishes CD56bright from CD56dim intratumoral NK cells, we examined KLRF1 expression in CD56bright versus CD56dim NK cells using cohort of patients with invasive bladder cancer (n = 20, see Table S4 for clinicpathologic characteristics) and found that KLRF1 expression, as measured by MFI, was significantly increased in CD56bright NK cells compared with CD56dim NK cells (Figure 2A).