STAT3 and posterior cortical atrophy: Conversely, in AI PAcP-null PCa cells, ectopic expression of PAcP results in decreased pTyr1221/2 of ErbB-2 and blocks its downstream signaling, which leads to cell growth suppression through the inactivation of p52Shc, ERK1/2, Akt, Src, STAT-3, and STAT-5 [15].