PTEN and cancer: However, recent studies show that in addition to BRCA deficiency, deficiency in other proteins required for homologous recombination (HR) including RAD51 [31], Fanconi anemia complementation group (FANC)D2 [32], FANCA [33], phosphatase and tensin homolog (PTEN) [34], Ligase-4 [35], partner and localizer of BRCA2 (PALB2) [36], CHK [37] can all sensitize cancer cells to PARPi.