MAPK1 and cancer: Increased ERK and p38 MAPK signaling have been reported to contribute towards chemoresistance.54, 55 There are also reports which suggest that inhibition of GSK3 might help the cells to overcome chemoresistance.56, 57 Our earlier studies showed that invasive cancer cells have higher levels of POPX2 and that cells with high levels of POPX2 also exhibit higher ERK activities.6, 8 We also found that knocking down POPX2 leads to lower GSK3 activities.