MAPK3 and familial pancreatic carcinoma: Activation of ERK5 was not detectable in our studies (data not shown) In contrast, activated (phospholylated) ERK1/2 was significantly reduced in all PTK6-gene-silenced pancreatic cancer cells compared to their corresponding control cells, while forced overexpression of PTK6 induced activation of ERK1/2 in both Panc1 and MIAPaCa2 cells (Figure 4A.B).