PFN1 and infection: To further verify these results with other siRNAs, we generated a tetracycline-inducible Pfn1 shRNA (this targeting sequence is also distinct from the constitutive Pfn1 shRNA and smart-pool Pfn1 siRNAs as described in previous experiments) expressing stable subline of MDA-231 cells through lentiviral infection and confirmed KD of Pfn1 upon doxycycline (dox) treatment (supplementary Fig S9A).