C Probabilities of output signals at 300s varied with force-dependent off-rates of the three ligands, MICA, MICB and ULBP3. Off-rates at different mechanical forces measured by experiments had been marked by specific symbols: pentagram, square, circle and right-pointing triangle represented off-rates at 0 pN, 5 pN, 10 pN and 15 pN, respectively. 