BMP4 and pancreatic insulinoma: In the present study, we found that changes to the Protocol #2 culture medium, namely adding BMP4, using DMEM instead of IMDM/F12, eliminating the N2 and B27 supplements, culturing the cells in 3D non-adherent structures, i.e. Protocol #4, dramatically increased Ins1 mRNA levels up to 100% of the normalized values seen in βTC6 insulinoma cell line.