PLA

PLA was performed using the Duolink In Situ Kit (Sigma) according to the manufacturer’s instructions. The following antibodies were used: LIN9 (Bethyl, A300-BL2981; 1:150), B-MYB phospho-T487 (ab76009; 1:100), YAP (Santa Cruz Biotechnology, sc-101199; 1:200). For secondary staining, samples were incubated for 45 minutes with the following antibodies: cTnT (DSHB; 1:50) or α-HA (Sigma, 1:200). After washing several times with buffer A, samples were incubated with for 20 minutes with secondary antibody: α-IgG2a conjugated to Alexa 488 (Thermo Fisher Scientific) and Hoechst 33258 (Sigma). Pictures were taken with an inverted Leica DMI 6000B microscope equipped with a Prior Lumen 200 fluorescence light source and a Leica DFC350 FX digital camera.