Fig. 4

FGFR2 isoform switch triggers PKCε activation, as well as induction of EMT. HaCaT cells were transfected with siRNA for ESRP1 or with an unrelated siRNA (Cx siRNA), as control, and then left untreated or stimulated with FGF7 or FGF2, as above. a Western blot analysis shows that ESRP1 siRNA induces an efficient depletion of ESRP1. Equal loading was assessed with the anti-actin antibody. The densitometric analysis was performed as reported above. b Real-time RT-PCR shows that ESRP1 silencing leads to the decrease of FGFR2b expression and to the appearance of FGFR2c mRNA transcript levels. HFs are used as a positive control for FGFR2c expression. Results are expressed as mean value ± SE. Student’s t test was performed and significance levels were defined as p < 0.05. **p < 0.01. c, d Biochemical approaches show that ESRP1 depletion is sufficient to make HaCaT cells responsive to FGF2 in terms of PKCε activation/phosphorylation and EMT induction, as demonstrated by E-cadherin repression and N-cadherin appearance. Equal loading was assessed with the anti-actin antibody. The densitometric analysis and Student t test were performed as reported above: *p < 0.05, ** p < 0.01. e Real-time RT-PCR shows that ESRP1 depletion, upon FGF2 stimulation, induces the up-regulation of the three EMT-related transcription factors Snail1, STAT3 and FRA1. Results are expressed as mean value ± SE. Student’s t test was performed and significance levels were defined as p < 0.05. *p < 0.05