ERG and posterior cortical atrophy: In opposition to the dramatic effect observed in PNT2‐ERG cells, in VCaP cells, the combination therapy did not show to significantly impair 3D cell growth, suggesting that the Erlotinib/TTI‐101 efficacy observed in early ERG‐driven PCa cell models may be lost with disease progression, with cells becoming “EGFR/STAT3 independent.” In line with this, stimuli with EGF in VCaP cells did not change p‐EGFR expression, supporting the hypothesis that other HER receptors, namely, HER2 and HER3, which heterodimerize with EGFR [46], may be activated upon EGF stimuli in ERG‐overexpressing PCa cells.