Figure 14: Most important targets of gga-miR-302b-5p and gga-miR-302-3p miRNAs. The main molecular targets for the studied miRNAs have been presented. The molecular pathways and targets for gga-miR-302b-5p are on the left side and for gga-miR-302b-3p on the right side. MAKP signalling is responsible for maintaining pluripotency and proliferation in mammals. It can be activated by a series of intrinsic and extrinsic stimulatory signals. In chickens, gga-miR-302b-5p controls the proliferation rate via MAPK signalling. In the case of low-proliferating PGC cell lines, gga-miR-302b-3p expression was high. It can be assumed that the high gga-miR-302b-3p expression somehow causes downregulation of pathways promoting proliferation, thereby causing cell cycle arrest at the G1 stage. gga-miR-302b-5p was found to be highly expressed in high-proliferating PGC lines. Hence, it can be hypothesized that probably the high expression of gga-miR-302b-5p is contributed in controlling throughout its molecular targets in the MAPK signalling pathway. miR-302b-5p probably by inhibiting the MAPK pathway components can cause high proliferation rate in PGC lines, and miR-302a is responsible for the fast transition from the G1 to S phase in the cell cycle [15].