Schematic of RNAi screen with analysis of fumarate levels throughout the screen. (A) Schematic of FH synthetic lethality screening strategy. Briefly, the screen involves three steps: (i) cell transduction with a library of shRNA agents; (ii) splitting the culture and silencing FH in one subculture; (iii) quantifying shRNA agent abundance by means of barcode sequencing. The expression of different shRNAs can have lethal (red), synthetic lethal (yellow), synthetic rescue (blue), or no effect (green) on the proliferation of each cell during the screen. (B) Residual FH mRNA levels at indicated times post siRNA transfection. (C) Residual FH protein level at indicated times post siRNA transfection.