NAPRT and cancer: Excluding the possible involvement of secondary targets in the distinct response of certain NAPRT-positive cancer cell lines to FK866 and A4276 (Figure 4B-E, and Figure S5B), we propose that the optimal, yet not excessively stringent, NAMPT inhibitory effect of A4276 is a critical factor contributing to its ability to spare NAPRT-positive non-EMT cancer cell lines.